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Duchochois







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Title: Photographic Reproduction Processes



Author: P.C. Duchochois



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Language: English



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***START OF THE PROJECT GUTENBERG EBOOK PHOTOGRAPHIC REPRODUCTION PROCESSES***











Photographic Reproduction Processes



A Practical Treatise of the Photo-Impressions Without Silver Salts

By P.C. Duchochois



New York

The Scovill & Adams Company

423 Broome Street.

1891











CONTENTS





INTRODUCTION.

THE DESIGNS.

THE CYANOTYPE OR BLUE PROCESS.

THE CYANOFER. (Pellet's Process.)

THE BLACK OR INK PROCESS. (Ferro-tannate Process.)

THE CUPROTYPE. (Burnett's Process.)

THE ANILINE PROCESS.

THE PRIMULINE OR DIAZOTYPE PROCESS.

TRACING PROCESS ON METAL.

GRAPHOTYPY.

THE URANOTYPE.

THE PLATINOTYPE.

   ARTIGUES' PROCESS

   THE CARBON PROCESS.

   APPENDIX.











ILLUSTRATIONS





A Tournette

Chardon's method of coating











PREPARER'S NOTE





Please remember that this book was published over a century ago, long

before today's chemical safety standards.  Please get expert advice before

attempting to perform any of the procedures described in this book.











AUTHORS QUOTED





Artigues.

Bevan, E.J.

Bingham

Borlinetto

Brasseur, Chs.

Buckle.

Burnett, C. J.

Chardon

Cheysson

Colas.

Cooper, H.

Cross, C. F.

De la Blanchere, H.

De St. Florent

Draper, Dr. John

Ducos du Hauron

Dumoulin, E.

Endemann,H.

Fisch, A.

Godefroy.

Green, A. G.

Graubassi

Harman, Alfred.

Herschel, Sir John.

Houdoy

Huebl, Baron.

Hunt, Robert

Liesegang, Dr. L.

Loeffler, J.

Monckhoven, Dr Von.

Niepce, de St. Victor

Obernetter, J. B.

Pellet.

Persoz.

Phipson, Dr.

Pizzighelli, Captain J.

Poitevin, A.

Roy, Paul

Sella, V. J.

Smee, Professor

Stephanowski, Karl.

Swan, J. W.

Willis, William

Wothly, J.

X.













INTRODUCTION.





The photographic processes with the salts of iron are all derived from the

researches of Sir John Herschel. The investigations of that great

philosopher are so valuable, so full of instructions that we are led to

reprint them, together with those of Mr. C. J. Burnett, on the salts of

uranium, etc., as an Introduction.  It will be seen that the process by

which blue prints are to-day obtained is exactly that Sir John Herschel

devised in 1840.



"It is no longer an insulated and anomalous affection of certain salts of

silver or gold, but one which, doubtless, in a greater or less degree,

pervades all nature, and connects itself intimately with the mechanism by

which chemical combination and decomposition is operated.  The general

instability of organic combinations might lead us to expect the occurrence

of numerous and remarkable cases of this affection among bodies of that

class, but among metallic and other elements inorganically arranged,

instances enough have already appeared, and more are daily presenting

themselves, to justify its extension to all cases in which chemical

elements may be supposed combined with a certain degree of laxity, and so

to speak in a _tottering equilibrium_.  There can be no doubt that the

process, in a great majority, if not in all cases, which have been noticed

among inorganic substances, is a deoxidizing one, so far as the more

refrangible rays are concerned.  It is obviously so in the cases of gold

and silver.  In the case of the bichromate of potash it is most probable

that an atom of oxygen is parted with, and so of many others.  A beautiful

example of such deoxidizing action on a non-argentine compound has lately

occurred to me in the examination of that interesting salt, the

ferrosesquicyanuret of potassium described by Mr. Smee in the

_Philosophical Magazine_, No. 109, September, 1840, and he has shown how

to manufacture in abundance and purity, by voltaic action on the common or

yellow ferrocyanuret.  In this process nascent oxygen is absorbed,

hydrogen given off, and the characters of the resulting compound in

respect of the oxides of iron, forming as it does Prussian blue with proto

salts, indicate an excess of electro-negative energy, a disposition to

part with oxygen, or which is the same thing, to absorb hydrogen (in the

presence of moisture), and thereby to return to its pristine state, under

circumstances of moderate solicitation, such as the affinity of protoxide

of iron (for instance) for an additional dose of oxygen, etc."



"Paper simply washed with a solution of this salt is highly sensitive to

the action of the light.  Prussian blue is deposited (the base being

necessarily supplied by the destruction of one portion of the acid, and

the acid by the destruction of another).  After half an hour or an hour's

exposure to sunshine, a very beautiful negative photograph is the result,

to fix which, all that is necessary is to soak it in water in which a

little sulphate of soda is dissolved.  While dry the impression is of a

dove color or lavender blue, which has a curious and striking effect on

the greenish yellow ground of the paper produced by the saline solution.

After washing the ground color disappears and the photograph becomes

bright blue on a white ground.  If too long exposed, it gets

'over-sunned,' and the tint has a brownish or yellowish tendency, which,

however, is removed in fixing; but no increase of intensity beyond a

certain point is obtained by the continuance of exposure."



"If paper be washed with a solution of ammonio-citrate of iron and dried

and then a wash passed over it of the yellow ferro-cyanuret of potassium,

there is no immediate formation of true Prussian blue, but the paper

rapidly acquires a violet-purple color, which deepens after a few minutes,

as it dries, to almost absolute blackness.  In this state it is a positive

photographic paper of high sensibility, and gives pictures of great depth

and sharpness, but with this peculiarity, that they darken again

spontaneously on exposure to the air in darkness, and are soon

obliterated.  The paper, however, remains susceptible to light, and

capable of receiving other pictures, which in their turn fade, without any

possibility (so far as I can see) of arresting them, which is to be

regretted, as they are very beautiful, and the paper of such easy

preparation.  If washed with ammonia or its carbonate, they are for a few

moments entirely obliterated, _but presently reappear with reversed lights

and shades_.  In this state they are fixed, and the ammonia, with all that

it will dissolve, being removed by washing in water, their color becomes a

pure Prussian blue, which deepens much by keeping.  If the solution be

mixed there results a very dark violet-colored ink, which may be kept

uninjured in an opaque bottle, and will readily furnish by a single wash

at a moment's notice the positive paper in question, which is most

sensitive when wet."



"It seems at first sight natural to refer these curious and complex

changes to the instability of the cyanic compounds; and that this opinion

is to a certain extent correct is proved by the photographic impressions

obtained on papers to which no iron has been added beyond what exists in

the ferrocyanic salts themselves.  Nevertheless, the following experiments

abundantly prove that in several of the changes above described, the

_immediate action_ of the solar rays is not exerted on these salts, but on

the iron contained in the ferruginous solution added to them, which it

deoxidizes or otherwise alters, thereby presenting it to the ferrocyanic

salts in such a form as to precipitate the acids in combination with the

peroxide, or protoxide of iron, as the case may be.  To make this evident,

all that is necessary is _simply to leave out the ferrocyanate_ in the

preparation of the paper, which thus becomes reduced to a simple washing

over with the ammonio-citric solution.  Paper so washed is of a bright

yellow color, and is apparently little, but in reality highly sensitive to

photographic action. Exposed to strong sunshine, for some time indeed, its

bright yellow tint is dulled into an ochrey hue, or even to gray, but the

change altogether amounts to a moderate percentage of the total light

reflected, and in short exposures is such as would easily escape notice.

Nevertheless, if a slip of this paper be held for only four or five

seconds in the sun (the effect of which is quite imperceptible to the

eye), and when withdrawn into the shade be washed over with the

ferrosesquicyanate of potash, a considerable deposit of Prussian blue

takes place on the sunned part, and none whatever on the rest; so that on

washing the whole with water, a pretty strong blue impression is left,

demonstrating the reduction of iron in that portion of the paper to the

state of protoxide.  The effect in question is not, it should be observed,

peculiar to ammonio-nitrate of iron."



"The ammonio and potasso-tartrate fully possess and the perchloride

_exactly neutralized_ partakes of the same property; but the experiment is

far more neatly made and succeeds better with the other salts."



"The varieties of cyanotype processes seem to be innumerable, but that

which I shall now describe deserves particular notice not only for its

pre-eminent beauty while in progress, but as illustrating the peculiar

power of the ammoniacal and other parsalts of iron above-mentioned to

receive a latent picture susceptible of development by a great variety of

stimuli.  This process consists in simply passing over the

ammonio-citrated paper on which such a latent picture has been impressed,

_very sparingly and evenly_, a wash of the solution of the common yellow

ferrocyanate (prussiate) of potash.  The latent picture, if not so faint

as to be quite invisible (and for this purpose it should not be so), is

negative.  As soon as the liquid is applied, which cannot be in too thin a

film, the negative picture vanishes, and by very slow degrees is replaced

by a positive one of a violet blue color on a greenish yellow ground,

which at a certain moment possesses a high degree of sharpness and

singular beauty and delicacy of tint.  If at this instant it be thrown

into water, it passes immediately to a Prussian blue, losing, at the same

time, however, much of its sharpness, and sometimes indeed becoming quite

blotty and confused."



"To prevent this confusion gum arabic may be added to the prussiated

solution, by which it is hindered from spreading unmanageably within the

pores of the paper, and the precipitated Prussian blue allowed time to

agglomerate and fix itself on the fibers. By the use of this ingredient

also, a much thinner and more equal film may be spread over the surface,

and _when perfectly dry_, if not sufficiently developed, the application

may be repeated. By operating thus I have occasionally (though rarely)

succeeded in producing pictures of great beauty and richness of effect,

which they retain (if not thrown in water) between the leaves of a

portfolio, and have a certain degree of fixity--fading in strong light and

recovering their tone in the dark. * * *"



"If paper be washed with a mixture of the solutions of ammonio-citrate of

iron and ferrosesquicyanate (red prussiate) of potash, so as to contain

the two salts in about equal proportions, and being then impressed with a

picture, be thrown into water and dried, a negative blue picture will be

produced.  This picture I have found to be susceptible of a very curious

transformation.  To effect this it must be washed with a solution of

protonitrate of mercury, which in a little time entirely discharges it.

The nitrate being thoroughly washed out and the picture dried, a smooth

iron is passed over it, somewhat hotter than is used for ironing linen,

but not sufficiently so to scorch or injure the paper.  The obliterated

picture immediately reappears, not blue, but brown. If kept for some weeks

in this state between the leaves of a portfolio, in complete darkness, it

fades, and at length almost disappears.  But what is very singular, a

fresh application of heat revives and restores it to its full intensity."



"This curious transformation is instructive in another way. It is not

operated by light, at least not by light alone. _A certain temperature_

must be attained, and that temperature suffices in complete darkness.

Nevertheless, I find that on exposing to a very concentrated spectrum

(collected by a lens of short focus) a slip of paper prepared as above

(that is to say, by washing with the mixed solutions, exposure to

sunshine, washing and discharging the uniform blue color so induced, as in

the last article), its whiteness is changed to a brown over the whole

region of the red and orange rays, _but not beyond_ the luminous spectrum.

Three conclusions seem unavoidable: first--that it is the heat of these

rays, not their light, which operates the change; second--that this heat

possesses a peculiar chemical quality which is not possessed by the purely

calorific rays outside of the visible spectrum, though far more intense;

and third--that the heat radiated from obscurely hot iron abounds

especially in rays analogous to those of the region of the spectrum above

indicated."



Sir John Herschel then proceeds to show that whatever be the state of the

iron in the double salts in question, its reduction by blue light to the

state of protoxide is indicated by many other agents.  "Thus, for

example," says Robert Hunt, "if a slip of paper prepared with the

ammonio-citrate of iron be exposed partially to sunshine, and then washed

with the bichromate of potash, the bichromate is deoxidized and

precipitated upon the sunned portion, just as it would be if directly

exposed to the sun's rays."



"I have proved this fact with a great number of preparations of cobalt,

nickel, bismuth, platinum and other salts which have been thought hitherto

to be insensitive to the solar agency; but if they are partially sunned

and then washed with nitrate of silver and put aside in the dark, the

metallic silver is slowly reduced upon the sunned portion.  In many

instances days were required to produce the visible picture; and in one

case paper being washed in the dark with neutral chloride of platinum was

sunned and then washed in the dark with nitrate of silver; it was some

weeks before the image made its appearance, but it was eventually

perfectly developed, and, when quite so, remained permanently impressed

upon the paper."



The following process, discovered at the same time as the cyanotype, and

termed chrysotype, is thus described by Sir John Herschel:



"In order to ascertain whether any portion of the iron in the double

ammoniacal salt employed has really undergone deoxidation, I had recourse

to a solution of gold, exactly neutralized by carbonate of soda.  The

proto-salts of iron, as is well known to chemists, precipitate gold in the

metallic state.  The effect proved exceedingly striking, and, as the

experiment will probably be repeated by others, I shall here describe it

ab initio.  Paper is to be washed with a moderately concentrated solution

of ammonio-citrate of iron and dried.  The strength of solution should be

such as to dry into a good yellow color, not at all brown.  In this state

it is ready to receive a photographic image, which may be impressed on it

either from nature in the camera obscura, or from an engraving on a frame

in sunshine.  The image so impressed is, however, very faint, and

sometimes hardly perceptible.  The moment it is removed from the frame or

camera, it must be washed over with a neutral solution of chloride of gold

of such strength as to have about the color of a sherry wine.  Instantly

the picture appears, not, indeed, at once of its full intensity, but

darkening with great rapidity up to a certain point, depending on the

strength of the solutions used, etc.  At this point nothing can surpass

the sharpness and perfection of detail of the resulting photograph.  To

arrest this process and to fix the picture (so far at least as the further

agency of light is concerned), it is to be thrown into water very slightly

acidulated with sulphuric acid, and well soaked, dried, washed with

hydrobromate of potash, rinsed and dried again. * * *"



"In point of _direct_ sensibility, the chrysotype paper is certainly

inferior to the calotype; but it is one of the most remarkable

peculiarities of gold as a photographic ingredient, that _extremely feeble

impressions once made by light go on afterwards, darkening spontaneously

and very slowly, apparently without limit so long as the least vestige of

unreduced chloride of gold remains in the paper_.  To illustrate this

curious and (so far as applications go) highly important property, I shall

mention incidentally the results of some experiments made during the late

fine weather on the habitudes of gold in presence of oxalic acid.  It is

well known to chemists that this acid, heated with solutions of gold,

precipitates the metal in its metallic state; it is upon this property

that Berzelius has founded his determination of the atomic weight of gold.

Light, as well as heat, also operates this precipitation; but to render it

effectual, several conditions are necessary:--First--the solution of gold

should be neutral, or at most _very_ slightly acid; secondly--the oxalic

acid must be added in the form of a neutral oxalate; and thirdly--it must

be present in a certain considerable quantity, which quantity must be

greater the greater the amount of free acid present in the chloride.

Under this condition, the gold is precipitated by light as a black powder

if the liquid be in any bulk; and if merely washed over paper, a stain is

produced, which, however feeble at first, under a certain dosage of the

chloride, oxalate and free acid, goes on increasing from day to day and

from week to week, when laid by in the dark and especially in a damp

atmosphere, till it acquires almost the black of ink; the unsunned portion

of the paper remaining unaffected, or so slightly as to render it almost

certain that what little action of the kind exists is due to the effect of

casual dispersed light incident in the preparation of the paper.  I have

before me a specimen of paper so treated in which the effect of thirty

seconds' exposure to sunshine was quite invisible at first, and which is

now of so intense a purple as may be well called black, while the unsunned

portion has acquired comparatively but a slight brown.  And (what is not a

little remarkable, and indicates that in the time of exposure mentioned

the _maximum_ of effect was attained) other portions of the same paper

exposed in graduated progression for longer times, viz., one minute, two

minutes, and three minutes, are not in the least perceptible degree darker

than the portion on which the light has acted during thirty seconds only."



"If paper prepared as above recommended for the chrysotype, either with

the ammonio-citrate or ammonio-tartrate of iron, and impressed, as in that

process, with a latent picture, be washed with nitrate of silver instead

of a solution of gold, a very sharp and beautiful picture is developed of

great intensity.  Its disclosure is not instantaneous; a few moments

elapse without apparent effect; the dark shades are then first touched in,

and by degrees the details appear, but much more slowly than in the case

of gold. In two or three minutes, however, the maximum of distinctness

will not fail to be obtained.  The picture may be fixed by the

hyposulphite of soda, which alone, I believe, can be fully depended on for

fixing argentic photographs."



"The best process for fixing the photographs prepared with gold is as

follows: As soon as the picture is satisfactorily brought out by the

auriferous liquid, it is to be rinsed in spring water, which must be three

times renewed, letting it remain in the third water five or ten minutes.

It is then to be blotted off and dried, after which it is to be washed on

both sides with a somewhat weak solution of hydriodate of potash.  If

there be any free chloride of gold present in the pores of the paper it

will be discolored, the lights passing to a ruddy brown; but they speedily

whiten again spontaneously, or at all events on throwing it (after lying a

minute or two) into fresh water, in which, being again rinsed and dried,

it is now perfectly fixed."



As the chrysotype will be no more referred to, we shall state, first, that

the image can be developed with a plain solution of silver nitrate or one

acidified with citric or any other organic acid, which generally gives a

brown impression that can be toned with an acid or alkaline gold bath, the

color varying with the solution employed; and secondly, that the process

may be employed to obtain outlines of any picture on paper or canvas to be

colored in oil-paints.  The impression developed with gold terchloride is

pale blue, _quite permanent_, and does not at all interfere with the work

of the artist.  The canvas should first be washed with a mixture of

alcohol and aqueous ammonia, then dried and rubbed with pumice stone

powder to give a _tooth_.  The modus operandi suggests itself.



The researches of Mr. C. J. Burnett on the application of uranium salts

and other compounds to photography are recorded in the _Photographic

Notes_ of Ths. Sutton for 1857.  We give in the following lines the most

interesting parts of the two papers of Mr. Burnett:



* * * "The next class of processes are dependent on the sensitiveness to

light of the salts of uranic oxide or sesquioxide of uranium, U2O3."



"In the first process, the paper being charged with the uranic salt and

exposed to the solar influence under the negative to be copied, is washed

with a solution of the ferridcyanide or red prussiate of potash.  The

'Harvest Scene' in the exhibition, being from an albumen negative lent me

by Mr. Ross, the well-known Edinburgh photographer, is an example, the

salt of the sesquioxide of uranium being in this case the hydrofluate, and

the time of exposure from the strength of the albumen negative fully an

hour of good sunshine.  I have used for the solution of the uranic oxide

for this process a variety of acids with very similar results; the

sensitiveness of the prepared paper to light varying much, however.  For

instance, a collodion negative with the hydrofluate paper producing a very

good print in half an hour of unsteady sun, while with a paper prepared

with the tartaric acid solution of the oxide, it gave an equally good

impression in less than five minutes of the same intermitting sunshine,

indicating thus a difference of sensitiveness of six to one in favor of

the tartrate."



"The rationale of this process is the reduction of the sesqui-oxide of

uranium, U2O3, on those parts of the paper exposed to the solar influence,

to a lower state of oxidation, the photo-oxide UO, the salts of which have

the property of forming with soluble alkaline ferridcyanides a rich

chocolate-brown precipitate, while the salts of the sesquioxide are

destitute of this reaction.  Hence the brown deposit on the parts of the

picture on which the sun has been allowed to act when the developing

solution is applied, and the absence of any such appearance on those parts

which have been protected from its influence."



"As to the manipulatory details of this process, the paper is floated on

the solution in a dark room and hung up to dry, and then preserved from

light in a portfolio.  If carefully secluded from light it appears to keep

well.  After exposure for the proper time under this negative, there is in

some cases scarcely any visible impression; while in other cases,

particularly when using the tartaric solution, I have found the impression

very distinguishable, of a brownish or blackish shade, although still

quite faint.  The development is best conducted by floating it, anything

like rubbing the picture being very objectionable."



"When the picture has fully come out, which is generally from three to ten

minutes at the very most, it is removed from the developing bath, placed

in cold water and washed very gently for a few minutes, the water being

frequently changed till it ceases to acquire a yellow tinge from the

dissolved red prussiate.  The picture is then drained from the water,

pressed between folds of blotting paper, dried (I dry in the dark), and

the process is complete. * * * I may state, as one recommendation of this

process to ladies and other lovers of clean hands, that any brown stains

left by it on the fingers or elsewhere are at once removable by a little

weak ammonia or soap and water. * * * I would particularly suggest, as

deserving of notice, the development of the salts of sesquioxide of

uranium, and still more iron, by the metals and metallic-cyanic alkaline

salts, as also by the mellonides and nitro-prussides, and the latter also

by itself and as developed by many metallic salts."



"I have since had the opportunity of trying the nitro-prusside of sodium,

which, by itself, gives a blue and white picture, in color like that

obtained from the red prussiate of potash."



"When mixed with a solution of ammonio-nitrate of copper, previous to its

application to the paper, the color obtained is pale purplish pink or

peach-blossom color. By mixing it in the same way with ammonio-oxalate of

sesquioxide of iron, we get a dull green picture, changeable through

intermediate stages into brown by alkaline carbonates, and that into a

_dirty_ black by gallic acid.  It may be well to know that the blue of the

picture given by the red prussiate in the process of Sir John Herschel may

be considerably modified or entirely changed to another color, in many

ways, without interfering with the purity of the white ground, by steeping

the picture, after the undecomposed red prussiate has been washed out, in

solution of salts of various metals, copper, uranium or cobalt, for

instance, and that the colors so produced may be modified as desired,

according to the stage at which the action is stopped."



"There remains but one class of uranic photographs to be described,

namely, that obtained when we develop with a salt of silver or gold (or

platinum?).  This class may be made to print much more rapidly than our

ordinary silver printing process, approaching sometimes more nearly to the

calotype development in this respect.  We get the _minutest details_ with

great fidelity, and the picture is effectually fixed by a simple fresh

hyposulphite solution, with a good color in many cases, or by ammonia,

which will be considered an advantage by those who hold the hyposulphite

an enemy to durability.  Different shades of color are produced according

to different solvent acids and different details.  I have got a good black

perfectly like that of an engraving, by the nitrate of uranic oxide,

developed by ammonio-nitrate of silver (or plain nitrate) and fixed by

plain hyposulphite without any coloring bath. * * * I have tried the

hyposulphite of gold on some of the silver-developed prints prepared with

the hydrofluate of the uranic oxide and fixed with ammonia, which had an

exceedingly unpleasant raw-red color, a very agreeable gray was at once

obtained.  I have succeeded in getting very beautiful impressions by

development of the uranic paper by chloride of gold alone."



In another communication to the _Photographic Notes_, more interesting

perhaps than the foregoing, Mr. Burnett says:



"The clearest and brightest of my results have been obtained by the action

of gallic acid, tannin, or especially a _mixture of tannin and carbonate

of ammonia_, potash or soda, on the blue pictures obtained by the

solarization of paper prepared with ferridcyanide of potassium,

ferrocyanide or ferridcyanide of ammonium. * * * I have also experimented

with the bichromate and iron, with gallic, tannin and other developer; but

I must confess to not having been, in this particular way, so successful

as Mr. Sella appears to have been in the preservation of the whites, owing

possibly to my not having taken the trouble to wash out sufficiently the

iron before toning."(1)



"I have experimented most extensively in many ways with the chromates and

bichromates, and have succeeded in various ways in getting _very good_

results.  A very capital process for many purposes is to float or steep

your paper in a mixed solution of bichromate of potash and sulphate of

copper.  As for E. Hunt's chromotype process," (2) I have mixed gelatine,

or occasionally grape sugar, or both, with the solution, but instead of

developing it by a silver solution, as in the chromotype, wash out the

salts unacted on by light, and develop by floating on a solution of

ferrocyanide of potassium.  The color of the red copper salt which now

forms the picture may be modified or changed in many ways, viz., by

soaking the picture, after the ferrocyanide of potassium has been washed

out of the lights, in a solution of sulphate of iron (or the iron salt

may, but not so advantageously, have been applied to the picture before

the application of the ferrocyanide).  Solutions of chloride of tin,

gallic and tannic acids, alone or with alkalies or alkaline carbonates,

may also be employed to modify or change the color.  Instead of developing

by ferrocyanide you may develop by the cobalt or chromo-cyanogen salts, or

by an alkaline _mellonide_ arsenite, etc.  Sulphureted hydrogen, or a

sulphide, will give a _brown_, or _black_ tone, which may be protected

against oxygen and dampness by a resinous varnish.



"Of all the simple pictures obtainable with bichromated papers, without

complications or other tonings, those obtainable by the combination of a

salt (say the sulphate) of _manganese_, with the bichromate in the paper

preparation, are about the best; these pictures being, however, capable of

being toned and modified in many different ways if desired.  This may be

accomplished by the use of toning baths of ferridcyanide or ferrocyanide,

or other metal cyanogen salts, etc., or by either mixing the salts of

other metals, as copper or iron, with the cyanic toning baths, or using

them in the original solution, or by soaking the paper in them, as in

Sella's process, previously to the application of the metal cyanic,

mellonic or other toning baths.  Alkalies and alkaline carbonates may also

be used to remove the chromic acid, and leave a subsalt, or the very

stable oxide or carbonate of manganese, which may be peroxidized by the

use of chloride of lime, peroxide of hydrogen, or ozone."



"In all the processes with metallic salts, alone with bichromates, the use

of sized or unsized paper along with gelatine, etc., has some advantages.

I have got good results by such processes on albumen paper, the albumen

tending to prevent mealiness in the print; also on paper soaked in

gelatine before the application of the bichromic solution. * * * There is

great interest connected with the action of all such papers, along with

the tannin and vegetable coloring matters.  I have long been of opinion

that by the steeping of papers or textile fabrics, containing the salts

not only of iron, as recommended by Mr. Sella, but of tin, copper,

bismuth, lead, etc., in solutions of cochineal, red cabbage, beetroot,

grass or the most ordinary foliage, etc., that the most useful results

might be obtained; though for _certain_ permanence I am not sure but that

some of the other processes which I have briefly run over with the

cyanogen acid salts or metallic acid salts, as precipitators, may be more

to be depended upon.  The processes with _precipitated oxides_, such as

the one with manganese and similar ones, with other metals which I have

described, I also consider as deserving of more attention than almost any

processes which have been stated, on the score of probable permanence; but

perhaps the best process for black, or generally useful neutral tint,

without silver, that has yet been offered to the public, I believe to be

the process alluded to with the bichromate of potash and sulphate of

copper, toned by an iron salt.  *  *  *  This process, the cuprotype (as

also the uranotype and manganotype) is applicable perfectly to films of

_albumen_ or gelatine on glass or porcelain, textile fabrics, parchment,

paper, tiles and many other substances besides paper."











THE DESIGNS.









                      HOW TO MAKE A NEGATIVE DRAWING





The drawing paper for designs to be reproduced by the cyantotype and the

other processes described in this book should be of a fine texture, free

from opacities and very white; and, as the design must serve as a cliche

it is a sine qua non that it be drawn with a very black ink and with

well-fed lines, especially those which are very fine.  To obtain a

complete opacity, and, at the same time, to keep the ink quite fluid,

which gives great facility to the designer, one adds some gamboge (or

burnt sienna) to the India ink.  The ink of Bourgeois, which is compounded

with yellow and can be diluted as easily as India ink, is excellent, so is

also the American ink of Higgins.(3)



As much as possible it is desirable to replace the colored lines

indicating the constructions, the axis, projections, etc., by differently

punctuated lines made with India ink.  However, if the use of colors be

obligatory on the original design, one should trace the red lines with

very thick vermilion or sienna, the yellow lines with gamboge, and the

blue and green lines with a thick mixture of Prussian blue and chrome

yellow in different proportions.



One must abstain from applying washes of any tints on the original. If

necessary they should be brushed over when the reproductions are made;

moreover they can be often replaced by cross-lines more or less open, and

the shadowing represented by thicker but not closer lines.



Tracing paper is recommended instead of linen, which latter, on account of

its thickness and granulation, gives less satisfactory results in regard

to the transparency of the ground and the continuity of the lines.



To reproduce a design on ordinary paper--not too thick--or an engraving,

etc., the paper is rendered transparent by rubbing over on the back of the

original a solution of 3 parts in volume of castor oil in 10 parts of

alcohol, by means of a small sponge.  When the paper is quite transparent,

the oil in excess is removed by pressure between sheets of blotting paper,

and the paper dried before the fire or spontaneously.  The design so

treated is not in the least injured, for it assumes its primitive

condition by dissolving the oil from the paper by immersion into strong

alcohol, which it is necessary to renew once or twice, then rinsing in

alcoholized water if the drawing be in India ink, or simply in water in

the case of an engraving, and finally drying between sheets of blotting

paper.



Instead of an alcoholic solution of castor oil, vaseline can be employed.

The paper is more transparent.



The method by which are made negative drawings, that is, those which can

be used as negative cliches to reproduce the design in black lines on a

white ground, is thus described by Mr. Cheysson, wlio originated it, in a

manual published by the Department of Public Works of France, from which

we have borrowed most of the above instructions for the drawing of designs

suitable for the photo-reproduction processes:(4)



"One can avoid the necessity of making a negative from the original

drawing by transforming the drawing itself into a negative."



"To that effect it suffices to draw with lithographic ink, then to cover

the paper with aniline brown, and, after drying, to wash it with

turpentine oil which dissolves the lithographic ink without altering the

aniline.  The lines appear then white on a brown ground impervious to

light (that is, non-actinic).  The design is thus transformed into a

negative, and can yield positive impressions with paper sensitized with

silver salts, the ferriprussiate or the bichromate of potash.  The

lithographic ink should be very black and the lines well fed."



"When the drawing is finished it is placed on a board lined with sheets of

blotting paper, then one spreads all over it the aniline brown with a

brush, and, lastly, after drying, the paper is carefully rubbed with a

bung of cotton or a rag imbued with turpentine until the lines of the

design are dissolved."



In our practice we have often taken a negative cliche from drawings made

in the ordinary manner, without the aid of the camera obscura (which would

have been too expensive for drawings of a certain size), by simply

printing a proof by contact on plain or albumenized silvered paper, and

fixing, without toning, in a new solution of sodium thiosulphate, then

washing as usual.   The proofs thus obtained from designs drawn with an

opaque ink, which allows a long insulation and, therefore, yields an

intense reduction, are of a deep brick-red color, quite non-actinic, and

give very good positives by the Artigues process.



N.B.--Paper in drying never assumes its original shape; it is, therefore,

necessary to make the figures on the reproductions from plans when they

are not on the originals.









                         CHOICE OF PAPER. SIZING.





In all the photographic processes by precipitation of metallic oxides the

quality of the paper has a great influence on the results. When the paper

is not well sized and not well calendered, the sensitizing solution is

absorbed, instead of simply impregnating the surface of the paper, and not

only the image is sunk in and its sharpness impaired, but good whites can

never be obtained, especially if the image should be toned, owing to the

impossibility of eliminating the metallic salts not acted on, that is, not

reduced by the action of light which the fibers of the paper mechanically

retain.



The "endless" rolls of paper, 54: inches wide--or "blue print paper," as it

is sometimes termed--of Blanchet freres et Kleber, of Rives, better known

as "Rives' paper", that of Johannot, of Annonay (France), and the

Steinbach (Saxe) paper are recommended.



For small prints from negatives in half tone the positive paper, 18x22

inches, of Rives or Saxe, should be preferred to the heavy kind.  It is

advisable to size it, so that the impressions be entirely formed on the

surface of the paper.  Moreover, an additional sizing is always

advantageous, whatever be the photographic process employed, to prevent

the imbibition of the sensitizing compound and to obtain more brilliant

and vigorous images, for the iron, chromium, uranium and other metallic

soluble salts require the presence of an organic matter (alcohol, ether,

gum arabic, glucose, caseine, etc.) to be reduced by the agency of light;

and as a consequence, the greater, within certain limits, of course, the

amount of organic matters, and the more thoroughly they are mixed with the

salts, the more sensitive the preparation and the better the results.



Arrowroot is the best sizing for our purposes.  Gelatine may be employed,

albumen also, but the coating should be insolubized when applied on the

paper and dry.



_Sizing with Arrowroot._--In a porcelain dish diffuse 4 parts of powdered

arrowroot and one part of liquid glucose in 200 parts of distilled or rain

water and dissolve by heat over an alcohol lamp, stirring all the while.

Let the solution boil for an instant, and when the paste is homogeneous

let it cool down and then remove the skin formed on its surface and strain

it through a fine canvas.  Now provide with three small sponges free from

gritty matters and cleaned in water, and nail by the four corners, one

over the other, felt size uppermost, as many sheets of paper as you wish

to size on a board somewhat smaller than the paper.  This done, with one

of the sponges take a small quantity of the arrowroot and, brushing it

length-way and cross-way, spread the paste into an even layer, then, by

rubbing very lightly with the second sponge, efface the striae and smooth

the coating as well as possible.  The third sponge serves to remove the

excess of paste when too much is at first spread on.  From six to seven

sheets of paper, 18x22, can be sized with the quantity of arrowroot paste

above given.



Another, but not quite so effective a manner of sizing although sufficient

for the cyanotype, is the following, employed by Mr. Pizzighelli for the

paper used in the platinotypic process:



Ten parts of arrowroot are powdered in a mortar with a little water and

then mixed by small quantities to 800 parts of boiling water. After a few

minutes 200 parts of alcohol are added and the mixture filtered.  The

paper is immersed for two or three minutes in the warm solution and hung

up to dry.



_Sizing, with Gelatine._--Dissolve at a temperature of about 140 deg. Fahr.

(60 deg. C.) 10 parts of good gelatine in 800 parts of water, then add 200

parts of alcohol and 3 parts of alum dissolved in a little water.  Filter

and prepare the paper by immersion as above directed.  The gelatinized

paper when dry should be prepared a second time and dried by hanging it up

in the opposite direction in order to obtain an even coating.











THE CYANOTYPE OR BLUE PROCESS.





_This process gives white impressions on a blue ground with diapositives

or drawings on transparent or semi-transparent materials, and blue

impressions on a white ground from negatives._  It is commonly known under

the names of "blue print process," "negative ferrotype process" and

"ferro-prussiate process."



The process is indeed exceedingly simple.  A sheet of paper, impregnated

or sensitized, as it is termed, with a solution of ferric citrate and

ferricyanate is impressed under a cliche,(5) then immersed in pure water,

whereby the image is developed and at the same time fixed. It is on

account of the great advantages offered by its simplicity that this

process is generally preferred by civil engineers and architects for the

reproduction of their plans.



The sensitizing solution is prepared in mixing by equal volumes the two

solutions following:



A.   Iron, ammonio       20 parts

     citrate

     Water               100 parts

B.   Potassium           15 parts

     ferricyanate (red

     prussiate)

     Water               100 parts



Although the mixture keeps pretty well for a certain period in the dark,

it is best to prepare only the quantity wanted for actual use.(6)



The paper is preferably sensitized in operating as follows:



Take hold of the paper by the two opposite corners and fold it into a

loop, lay it on the iron solution, the center of the sheet first placed in

contact with the liquid, and then gradually spread it by lowering the

corners with a little pressure.  No solution should run over on the back

of the paper; it would be a cause of stain.  This done, and without

allowing the liquid to penetrate _in_ the paper, immediately take hold of

the two corners near the body and withdraw the paper by dragging it over

on a glass rod for this purpose fixed on the edge of the tray.  Now pin up

the paper to dry, which should be done rapidly, and sensitize a second

time in proceeding in the same manner.  If this second sensitizing be

found objectionable, let float the paper for no more than ten seconds; of

course this method of sensitizing is not applicable to prepare larger

sheets of paper.  In this case the paper is pinned by the four corners on

a drawing board or any other support, lined with blotting paper and

quickly brushed over with a sponge sparingly imbued with the sensitizing

mixture, so as to wet the paper with a very small excess of liquid.



The rationale of this manner of sensitizing is to impregnate only the very

surface of the paper with the ferric salts, and thereby to obtain an

intense blue with very good whites, which latter it would be impossible of

obtaining should the sensitizing solution be allowed to reach in the

fibers of the paper, for, in this condition, it is impossible, owing to

the exigencies of the process, to wash out thoroughly the iron salts to

prevent the chemical changes which cause the whites to be tinted blue.  It

is for this reason that better results are also obtained with well sized

papers.



The sensitizing should be done by a very diffused daylight, and the

drying, of course, in a dark room.  When sensitized the paper is yellowish

green.  It should be well dried for keeping, and rolled or wrapped in

orange or brown paper and preserved from the action of dampness and of the

air.  It does not keep well, however, no more than two or three months,

perhaps, in good condition; but the sooner it is employed the finer the

proofs, the better the whites and more rapidly is the paper impressed.



There is in the market a paper which keeps for a long time.  It is

prepared by adding a small quantity of gum arabic or of dextrine to the

sensitizing solution.  Good for the reproduction of line work, it does not

give very satisfactory results for pictures in half tones.



The following compound gives a paper much more sensitive, but not keeping

so long, than that prepared according to the formula previously given:



Tartaric acid               25 parts

Ferric chloride, solution   80 parts (in volume)

at 45 deg. Baume

Water                       100 parts



When the acid is dissolved, add gradually concentrated aqueous ammonia,

just enough to neutralize the solution--170 volumes, about.  The chemical

change consists in the formation of ferric tartrate.  Let cool the

solution, then, after adding the following, keep it in the dark:



Potassium ferricyanate   211/2 parts

Water                    100 parts



Another and very sensitive preparation is the following:



A.    Iron perchloride,   40 parts

      cryst

      Oxalic acid         10 parts

      Water               100 parts

B.    Potassium           20 parts

      ferricyanate

      Water               100 parts

Mix



_Printing._--The process we describe yields negative impressions, that is a

positive image from a negative cliche, and a negative image from a

positive cliche, exactly as the silver printing-out process ordinarily

employed in photography.  Consequently, for the production of non-reversed

proofs from plans, etc., the original drawing should be placed _face

downwards_ on the glass plate of the printing frame, and, upon the back,

the sensitive paper is laid and pressed into perfect contact by means of a

pad, felt or thick cloth.



The printing frame is that used by photographers. The lid is divided,

according to the side, in two, three and even four sections, held by

hinges and fastened for printing by as many cross-bars, in order that by

opening one section, from time to time, the operator can follow the

progressive changes resulting from the action of light on the iron salts.

To print, the frame should be placed in the light in such a manner as the

luminous rays fall perpendicularly upon the drawing or cliche.  The reason

of this is obvious, since the sensitive paper is not in direct contact

with the design, but separated by the material upon which it is drawn.



During the insolation--whose time depends necessarily from the more or less

transparency of the cliche, and, also, from the intensity of the

light(7)--the paper assumes first a violet tint, which gradually

intensifies to a dark shade; then this tint fades, becomes brownish, then

pale lilac, while the parts under the lines--that is, the design--upon which

the light has, therefore, no action, are visible by keeping the original

yellow-green tint of the prepared paper. It is when the lilac color is

produced that the exposure is sufficient.



To ascertain when the exposure is correct, a few black lines can be traced

on one of the edges of the margin of the design, and strips of the

sensitive paper placed upon them to serve as _tests_ in operating, as it

will be explained in the description of the Cyanofer process.  When one of

them is taken out and show, by being washed in water, a clear white line

on a deep blue ground, the exposure is at an end.  One understands that

the blue color of the ground is more or less intense according to time of

insolation, for the chemical actions between the reduced and the

non-reduced iron salts is so much more complete as the salts acted on are

more or less deoxidized, that is, reduced to ferrous salts; and that to

obtain the maximum of effect, which, therefore, depends on the allowable

time of exposure, the drawing ink should be opaque and non-actinic as far

as possible, because when, on testing, the lines are tinted the exposure

should be discontinued. However, a slight coloration of the lines is not

very objectionable, for it disappears by a longer washing after the

development.



The image is developed and fixed by washing in water two or three times

renewed.  The water must be free from calcareous salts; these salts

converting the iron into carbonates which impart an ochrey tinge to the

proof.   Rain water--any water in which no precipitate is thrown down by

the addition of a few drops of a weak solution of silver nitrate--may be

used with safety.



During the development the ground takes a blue color which rapidly

intensifies, while the iron compound, not acted on and imparting a yellow

green tint to the design, is washed out from the white paper.  If the

print has not been sufficiently exposed the ground remains pale blue, more

or less; the reason has been explained.  In this case the development

should be done quickly, as the blue is always discharged by washing.  On

the other hand, whenever the whites are tinted by excess of exposure, they

can be cleared partly or entirely by a prolonged immersion in water, but

the ground is also to some extent lightened.



When the proof is well developed and fixed, that is, when the soluble iron

salts are eliminated, the blue color can be brightened by adding to the

last but one washing water a small quantity of citric acid, or of

potassium bisulphate, or a little of a solution of hypochlorite of lime

(bleaching powder).



The action of light in this, as well as in the other photographic

processes with metallic salts described in this work, is one of

deoxidation, as shown by Herschel.  The chemical changes which produce the

blue precipitate is quite complicated.  It is evident that both the ferric

citrate and the ferric cyanate are partly reduced to ferrous salts under

the luminous influence, and react in presence of water with the unreduced

part of each of these compounds, the ferric citrate with the ferrous

cyanate forming Prussian blue (ferric-ferrocyanate), and the ferric

cyanate with the ferrous citrate giving rise to Turnbull's blue (ferrous

ferricyanate).  The blue of the print is consequently a mixture in a

certain proportion of the two compounds; and as the color of Prussian blue

is quite different from that of Turnbull's, it follows that by varying in

a certain measure the percentage of the two ferric salts forming the

sensitizing solution, the color of the blue may be varied thereby. Hence

the difference in the formulas given by different authors.(8)



The blue color of the image can be changed into black or dark green. But

to that purpose the paper should be, although not exactly necessary, well

sized as before directed, and sensitized with extra care to prevent the

imbibition of the iron solution into the paper. After exposure the proof

should necessarily be thoroughly washed to eliminate the soluble iron

salts, then immersed for a moment in water acidified with nitric acid,

1:100, and this done and without washing treated by a solution of aqueous

ammonia at 2 per 100 of water.  In this the blue color disappears, being

changed into a red brownish tint, which indicates that the Turnbull's and

Prussian blues are transformed, the former into ferroso-ferric hydrate,

with formation of ferrocyanate, and the latter into ferric hydrate.  It is

by the action of tannin (gallotannic acid) on the ferric oxides thus

formed that the black is produced, and by that of catechu-tannic acid

contained in the extract of catechu that one obtains a dark green, almost

black color.



To obtain the black tone it suffices to immerse the proof on its removal

from the ammoniacal in a solution of tannin at 5 per 100 of water, and

when toned, to wash it in a few changes of water.



The process to turn the blue color into a green was devised by Mr. Paul

Roy.  It is as follows: Dissolve 7 parts of borax in 100 parts of water,

and acidify the solution with sulphuric acid added drop by drop until the

litmus paper becomes red; then, in the same manner, neutralize with

aqueous ammonia not in excess, but just enough to show an alkaline

reaction; this done dissolve 1 part of powdered catechu and filter.  In

this the proof is immersed after development until the desired effect is

attained.  Wash, etc.



To clear the lines, or to make additions, or to write on the blue margin

of the proof a solution of potassium oxalate is employed. It dissolves the

blue without leaving scarcely any trace of it.  The solution can be

prepared by mixing the two solutions whose formula is given below:(9)



A.   Oxalic acid       10 parts

     Water             100 parts

B.   Caustic potassa   121/2 parts

     Water             100 parts



The blue prints are permanent.  When drying they darken a little from

oxidation; exposed to sunshine for some hours, they bleach considerably;

but in the shade the faded pictures progressively absorb oxygen from the

air and assume their original intensity and color in a period so much the

longer as the insulation has been more prolonged; it may take weeks if the

picture were much bleached.











THE CYANOFER. (PELLET'S PROCESS.)





_This process gives blue impressions on a white ground from positive

cliches, and white impressions on a blue ground from negative cliches._

It is termed "positive ferrotype process."



The cyanofer is an application of one of the numerous and useful

inventions for which photography is indebted to A. Poitevin.  In 1863 he

discovered that certain organic substances were rendered insoluble by

ferric chloride, and that they again became soluble; when under the

influence of light the ferric chloride has been reduced to a ferrous salt.

This curious phenomenon is the base of the process now to be described.

As usual the process has been modified by compounding the sensitive

solution in various ways and by minor details in the manner operating.

But although these modifications have rendered the process easier to work

with, there is not a great difference in the results obtained.  We give

two formulas.  Aside from the addition of gum arabic, which was suggested

by Mr. Pellet, and which constitutes the capital improvement of the

process, the formula is substantially that devised by Mr. Poitevin.



Prepare three solutions as follows:



A.   Gum arabic, best   50 parts

     quality

     Water              170 parts

B.   Tartaric acid      12 parts

     Water              80 parts

C.   Ferric chloride    35 parts in volume

     solution at 45

     deg. Baume



Mix gradually B to C, then C, by small quantities, in agitating briskly.

It is important to prepare the solution as directed, for by adding the

ferric chloride before tartaric acid, the gum arabic would be at once

coagulated.  When the ferric chloride is mixed, the solution at first

thickens, but becomes sufficiently fluid for use in a certain period.  It

does not keep, and should be employed the day it is made if possible.



The paper, which should be well sized and calendered, and which, when not

giving good results by too much absorbing the sensitive solution, must be

starched as before directed, is coated either by brushing or by floating.

By the first method a roll of paper five yards long can be prepared

without great trouble, and give, perhaps, better results than if prepared

by floating; but the latter method is by far the the most convenient: one

does not generally prepare by brushing sheets of paper larger than about

30x40 inches.



For brushing, the paper is pinned on a board, then, with a large badger

brush dipped in the sensitive solution, the latter is applied as evenly as

possible; after which, by lightly passing the brush over, the striae are

removed, the coating well equalized, and the paper hung up to dry.  The

coating should not be very thin, and, above all, not too thick, for then

it would require an unusually long exposure to allow the light acting

through the whole thickness of the film, which is a sine qua non to obtain

a clear ground, i.e., not stained blue.



To prepare by floating, pour the solution in a shallow tray, which needs

not to be more than 20x34 inches, 30 inches being the width of the drawing

paper usually employed; then roll the paper and place it on the solution.

Now, taking hold of it by two corners, draw it out slowly: the paper will

unroll by itself.  This operation can be done by diffused daylight, but,

of course, the paper should be dried in a dark room.  It dries rapidly.

Endless rolls are prepared by machinery.  To expose, the drawing is placed

in the printing frame, face downwards, and the sensitive paper laid over

it. The whole is then pressed into contact by interposing a cushion

between the lid of the frame and the paper, and exposed so that the rays

of light fall _perpendicularly_ upon it.



The cyanofer preparation is quite sensitive.  From half a minute to two

minutes exposure, according to the intensity of the light and the

thickness of the coating, is sufficient in sunshine to reproduce a drawing

made on the ordinary tracing paper.  In the shade, by a clear sky, the

exposure is about five times longer, and varies from half an hour to an

hour and more in cloudy weather, but then the design is seldom perfectly

sharp.



The progresses of the impression is followed by opening one side of the

printing frame and examining the proof. The exposure is sufficient when

the paper is tinged brown on the parts corresponding to the ground of the

design.  The image appears then negative, that is, yellowish on a tinged

ground.



Another and more safe method of ascertaining the correct time of exposure,

which can be employed concurrently with the other, is to place a few

strips of the same sheet of sensitive paper between the margin of the

design, upon which a few lines have been traced, and the paper, and,

without opening the frame, to draw one of them, from time to time, and dip

it in the developing solution.  If the whole strip be tinted blue, the

proof is not sufficiently exposed; but if the lines soon appear with an

intense coloration on the yellowish ground of the paper, and the latter do

not turn blue in a minute, at the most, the exposure is right.  By excess,

the lines are with difficulty developed or broken.



For developing, we provide with three wooden trays lined with lead or

gutta-percha, or, more economically, coated with yellow wax.  The wax is

melted, then applied very hot, and, when it is solidified and quite cold,

the coating is equalized with a hot iron, whereby the cracks produced by

the contraction of the wax when cooling are filled up.



One of these trays should contain a layer, about three-quarters of an inch

thick, of an almost saturated solution of potassium ferrocyanate (the

developer); the next be filled with water, and the third with water

acidified by sulphuric acid in the proportion of three per cent. in

volumes.



All this being ready, the margin of the proof is turned upwards--so as to

form a disk of which the outside is the impressed surface--in order that

the ferrocyanate solution does not find its way on the back of the proof,

which would produce stains.  Now the proof is laid, the lower edge first,

on the developer, and gradually lowered upon it, when, taking immediately

hold of it by the two corners nearest to the body, it is lifted out and

held upright to allow one following the development of the image; and,

presently, if any air-bubbles are seen on the proof, they should at once

be touched up with a brush wetted with the ferrocyanate solution; the

reason explains itself.



The image appears at once.  As soon as the fine lines are well defined,

the blue intense, and, especially, when the ground has a tendency to be

tinged blue, the proof is placed in the tray filled with water and in this

turned over two or three times, when it is immersed in the diluted

sulphuric acid.  In this bath the print acquires a deep blue coloration,

consisting of Prussian blue, and the ground becomes tinted with a blue

precipitate without adherence, which is easily washed off by throwing the

liquid on the proof with a wooden spatula, or, better, by rubbing with a

rag tied to a stick.  When the ground is cleared, and after three or four

minutes immersion to dissolve the iron salts acted on, the proof is rinsed

in water several times renewed to free it from acid, and hung to dry.



There are two causes of failures in this process, viz., over and

under-exposure. In the former case the fine lines are broken or washed out

in clearing the proof (which may also arise from the drawing made with an

ink not opaque enough); in the latter the ground is more or less stained.



The blue stains, the lines for corrections, etc., are erased with the the

potassic oxalate (_blue salving,_ as it is termed) whose formula has been

given.



The additions, corrections and writing are made with a _Prussian blue ink_

prepared by mixing the two following solutions:



A.   Ferric chloride,   4 parts

     dry

     Water              350 parts

B.   Potassium          15 parts

     ferrocyanate

     Water              250 parts



The precipitate being collected on a filter and washed until the water

commences to be tinged blue, is dissolved to the proper consistency in

about 400 parts of water. This ink does not corrode steel pens.



It has been stated that the cyanofer process keeps for years if preserved

from the combined action of dampness and the air.  The writer found in his

practice that the ferric salts in presence of the organic matters (the

sizes) acts as does potassium bichromate and renders, in a certain period,

the cyanofer film insoluble even after a prolonged insulation.  Paper

freshly prepared is always more sensitive and gives better whites and

generally finer results.(10)



The prints can be toned black in operating as in the cyonotype, but the

results are seldom good.



Captain Pizzighelli's formula is as follows: Prepare



A.   Gum arabic        15 parts

     Water             100 parts

B.   Ammonia ferric    45 parts

     citrate

     Water             100 parts

C.   Ferric chloride   45 parts

     Water             100 parts



For sensitizing mix _in order_:



Solution A   100 parts

Solution B   40 parts

Solution C   20 parts



The mixture very much thickens at first, but becomes sufficiently fluid

for use in a few hours.  It keeps well for two or three days. Leaving out

B and replacing it by rain water, this makes also a good solution for the

cyanotype.











THE BLACK OR INK PROCESS. (FERRO-TANNATE PROCESS.)





_This process gives black positive impressions on white ground from

positive cliches, and negative impressions from negative cliches._  It has

been attributed to Mr. Colas, but in reality it was invented by Mr.

Poitevin, who describes it as follows in his communication of May, 1860,

to the Societe Francaise de Photographie:



"I make a solution containing--"



Iron perchloride, cryst   10 parts

Tartaric acid             3 parts

Water                     100 parts



"I apply the paper on this mixture and let it dry spontaneously in the

dark, and at the moment of using it I completely desiccate it at a gentle

heat. Thus prepared the paper is of a deep yellow color.  Light decolors

it rapidly, and ten or twelve minutes' exposure through a positive cliche

suffices to well impress it, that is, to reduce in the whites the iron

perchloride to the state of protochloride."



"To print, one is guided by the decoloration of the paper, and even for

more facility I add to the solution of iron perchloride and tartaric acid

a small quantity of a solution of potassium sulphocyanide for the purpose

of obtaining a red tint, which is more visible and disappears also under

the influence of light in proportion to the decomposition of the

perchloride.  One obtains then after exposure a red design on the white

ground of the paper.  This red color is not permanent.  It even disappears

by keeping the proof in the dark."



"To develop and then to fix the design thus obtained I wash rapidly the

paper in ordinary water, or better, in water holding chalk in suspension.

The red coloration disappears, a part of the iron perchloride is washed

out, and in the parts which have not been acted on by light the

perchloride is transformed into sesquioxide.  I replace then the water by

solution of gallic acid or of tannin and the image progressively appears

in ink-black.  When I judge the image to be sufficiently intense I wash

the proof in rain water, in preference to ordinary water, which might

cause the gallic acid and tannin to turn brown. I sponge between sheets of

blotting paper and let the proof dry spontaneously."



"If in place of gallic acid I use a diluted solution of potassium

ferricyanide (red prussiate of potash), Prussian blue is formed in the

parts acted on by light.  The preparation is even sensitive enough to

permit one to obtain an impression in the camera obscura in developing by

the ferricyanide."



"As to the proofs in gallate (or tannate) of iron, they can be transformed

into Prussian blue in a solution of potassium ferrocyanide (yellow

prussiate of potash) slightly acidified by sulphuric acid."



The paper most suitable for this process is that which has been previously

well sized with starch, as explained in a special paragraph of this

pamphlet. Paper prepared with a film of coagulated albumen gives also good

results.  It may be prepared by brushing as well as by floating, but in

either case the paper should be wetted on the surface only and dried

rapidly at a temperature of about 115 deg. Fahr. (46 deg. C.) and kept in

a dry place.  It does not keep for more than from ten to fifteen days,

owing to the hygroscopicity of the iron compound.  Mr. Colas, who prepares

the paper for the Parisian market, I think, states that he avoids its

deterioration by keeping it wrapped in blotting paper, between two sheets

of India rubber, to exclude air and dampness.  Silvered albumen and plain

paper, well desiccated, could be kept in that way for a certain period,

especially if the blotting paper is impregnated with sodium bicarbonate

and well dried.



Mr. A. Fisch advises to discard the preliminary washing and to develop

just on the removal of the proofs from the printing frame.  In operating

in this manner the development is best made by floating, taking care that

the solution does not run off the back of the proof.



The developer may consist of a dilute solution of nutgalls or of



Tannin or gallic acid   4 parts

Oxalic acid             0.15 parts

Water                   1,000 parts



After developing the proof should be washed rapidly--under a jet of water,

if possible--for were the iron salt and the reagent not soon removed, or

any remain in the paper, the ground would be tinted violet.  And whatever

be the care taken, it very seldom occurs that the whites are pure when the

proof is dry.  This for half-tone pictures has not a great importance, but

for the reproductions of plans it is sometimes objectionable.  In fact it

must be acknowledged that none of the processes now at our disposal--if we

except the so-called Artigues process described further on--gives an

entirely satisfactory result.  A simple and expeditious process, yielding

intense black impressions on a white ground, is yet to be found for the

reproduction of plans, maps, etc., without resorting to a negative cliche

or drawing.











THE CUPROTYPE. (BURNETT'S PROCESS.)





_This process gives positive impressions from negative cliches._



Uranic nitrate   10 parts

Cupric nitrate   2 parts

Water            100 parts



Float for a minute strong, well-sized paper on this solution and let it

dry spontaneously in the dark.  Expose until the image is visible, then

develop by floating on a solution of potassium ferricyanide at 5 per 100

of water--the image appears at once with a rich brown color.  When

developed, wash it in several changes of water until the unaltered salts

are eliminated.  The proof is then fixed, and, if too intense, can be

reduced in water slightly acidified with hydrochloric acid.  A fine black

image is obtained by toning in a solution of platinic chloride at 1 per

100 of water.



The chemical actions giving rise to the formation of the metallic

ferrocyanide, of which the image consists, are quite complicated.  Under

the luminous agency the uranic nitrate is first reduced, then the uranous

oxide acts on the cupric nitrate, forming cupric oxide, which is finally

reduced to the metallic state.  This metal now converts the ferricyanate

in the ferro compound, which, by another action, forms both cupric and

uranic ferrocyanate.



The following uranium process gives black impressions:



In a saturated solution of tartaric acid dissolve freshly precipitated

ferric oxide, and keep the solution--ferric tartrate--in the dark.  To

prepare the sensitizing solution, dissolve 20 parts of uranic nitrate and

from 1 to 3 parts of tartaric acid in 100 parts of water, and add a small

quantity of ferric tartrate, the proportion varying with the tint desired:

an excess gives a blue black. With this solution brush the paper over,

and, when dry, expose under the negative cliche, then develop with a

solution of potassium ferricyanate at 4 per 100 of water. To fix, it

suffices to wash in water, renewed three or four times.



As pointed out by Mr. B. J. Burnett (see Introduction), many photographic

processes can be devised by basing them upon the various chemical changes,

of which uranous oxide, reduced by light from the uranic nitrate or

sulphate, is susceptible by means of metallic or organic reagents.



In the Appendix some of the most important processes, with or without

silver salts as reagents, will be described.











THE ANILINE PROCESS.





The aniline process was published in 1865, by Mr. Willis, the inventor of

the platinotype.(11) It is based on the oxidation of aniline by chromic

acid, thus: A sheet of paper brushed with a solution of potassium

bichromate and sulphuric acid, dried, and after insolation under a cliche

exposed to the fumes of aniline which, in reacting with the chromic

compound not reduced by light, forms a blue-black image.  _The process

gives, consequently, a positive impression from a positive cliche._



There are various methods of operating; we will briefly describe them.



        SENSITISING SOLUTION.

1.      Potassium            6 parts

        bichromate

        Sulphuric acid       6 parts

        Magnesium chloride   10 parts

        Water                150 parts



Willis recommended 10 parts of solid phosphoric acid instead of sulphuric

acid; the latter forms a preparation about twice more rapidly reduced.



2.   Potassium            10 parts

     bichromate

     Manganous sulphate   4 parts

     Potassium            20 parts

     bisulphate

     Water                300 parts

3.   Ammonium             5 parts

     bichromate

     Ammonium chloride    5 parts

     Cupric sulphate      1 part

     Sulphuric acid       8 parts

     Water                150 parts



Good well-sized paper should be employed. Rives is too tender and absorbs

too much.  Steinbach is better.  For small sizes, whatever be the paper

selected, it is well to size it with starch and, if possible, to calender

it on a hot steel plate, or, in lieu, to iron it.  This is not, however, a

sine qua non. The paper is sensitized by brushing or by floating.  To

sensitize by floating, it should be left but for a few seconds on the

solution and removed by dragging it on a glass rod in order to remove the

superfluous liquid.  Only the surface of the paper should be impregnated,

otherwise the whites would be more or less tinted and the image imbedded

not as sharp.



Sensitized, the paper must be dried as rapidly as possible. It does not

keep, and should be employed the day it is prepared or the day after,

keeping it well wrapped in paper.



As said above, it is exposed under a positive cliche, plans, designs,

etc., drawn on tracing paper or linen.  The more transparent the material,

the more rapid the chemical changes.  During the insolation--and it is very

short--the chromic compound is reduced, the parts corresponding to the

ground, that is, the transparent parts of the cliche, are discolored,

while those under the design remain unaltered; the image being, therefore,

faintly visible, and being formed of the chromic mixture, it is developed

by the fumes of aniline in a blue black tone.  Therefore, if the paper be

not sufficiently exposed, the ground is colored like the image, although

not as deeply, since the dye formed is proportionate to the more or less

quantity of unreduced compound, and if exposed too long the image is

imperfectly developed or not at all by excess.



The discoloration of the ground, which turns to a greenish hue, easily

indicates when the exposure is sufficient.  But, to ascertain it, the

beginner should use _tests_ as in the cyanofer process.  Mr. Endemann

regulates the time of exposure by partly covering a strip of the sensitive

paper with a piece of the tracing material upon which the design is made,

and exposing the whole until the covered part of the paper assumes the

same shade as the part directly exposed to light.



To develop the print is placed in the bottom of a tray, which is then

covered with a lid upon which is pinned blotting paper well imbued with an

aniline and benzine mixture, or the reverse; that is, exposing the print

fastened to the lid and placing the aniline on the bottom of the tray.

The tray should be hermetically closed; that is a condition to obtain a

fine and equal coloration.  For this purpose the lid should be well lined

with sheets of blotting paper and a weight placed over it during the

operation.  Large prints are necessarily developed in a fumigating box

made ad hoc.  The aniline solution consists of



Aniline (commercial for   8 parts

red)

Benzine, rectified        100 parts



In place of benzine, ether U.S.P., sp. grav. 0.837, may be used.



When the proof is not over-exposed the development commences in a few

minutes.  The image first takes a dirty black olive color which turns blue

in water, then the tone darkens to a dark-brownish tint.  The time of

exposure to the aniline fumes depends on the time of insolation; if short,

the ground is soon tinted, and consequently the development should then be

stopped; if over-exposed, the development proceeds slowly.  The darkest

tone is obtained by a rather full exposure which admits a long fumigation.

Sometimes the image takes a green color; it suffices then to wash the

proof in water rendered alkaline by a few drops of aqueous ammonia to

obtain the normal color.



To somewhat improve the tone of the image and, if objectionable, to remove

the chromic oxide which tinges the ground greenish, the proof should be

immersed in a dilute solution of sulphuric acid 1:100, then washed twice,

and finally passed in ammoniacal water 1:100.



Mr. Hermann Endemann has published, in 1866, the following process in the

_Journal of the American Chemical Society_, pp. 189 et seq.:



The paper, which must be well sized with glue, 1:50, is sensitized with

the following solution and exposed when dry, but still slightly damp:



A.   Potassium         1 ounce or 480

     bicarbonate       parts

     Salt              1 ounce or 480

                       parts

     Sodium vanadate   2/3 grain or 0.66

                       part

     Water             20 ounces or 9,600

                       parts

B.   Sulphuric acid    2 ounces or 960

                       parts

     Water             10 ounces or 4,800

                       parts



When cold mix to A.



"From the composition of the solution," says Mr. Endemann, "it is evident

that it must be strongly acid; but when this solution is exposed to light,

in the presence of the organic substances of the paper, the acidity of the

solution disappears, we obtain potassium and sodium sulphates, basic

chromium sulphate, salt and vanadic acid.  While, therefore, the unchanged

parts of the paper remain acid, the changed parts acquire a neutral

reaction, and while the first will readily assimilate bases, the second

will not.  Exposed in an atmosphere laden with water and aniline, the

aniline will be absorbed in those parts where the solution remains acid

and in proportion to the remaining acidity."



To develop the image the paper is spread over the opening of a frame

tightly placed on a pan, in the bottom of which is heated a solution of

aniline in water, 1:50, until the image appears brown, and for further

development in a box laden with steam water, which, according to Mr.

Endemann, requires two hours to obtain a deep black coloration.  To remove

the chromium compound the picture is immersed in a solution of aqueous

ammonia, 1:6, then washed and dried.



A few years ago the aniline process was improved by developing the image

with the aniline-benzine mixture vaporized by steam in a box made

specially for that purpose, whereby a reproduction can be obtained in less

than ten minutes.



In the photographic department of Messrs Poulson & Eger's Hecia

Architectural and Ornamental Iron Works, which is directed by Charles

Bilordeaux, this process is worked in the following manner:



The developing is made of sheet iron with a door sliding up and down, it

being balanced by a counterpoise, and provided with a chimney.  In the box

is a gutter, extending the whole length of the bottom, covered with muslin

and connected to a steam pipe; there is also a coil similarly connected.

After the insolation, which requires about one minute in sunshine, the

print is suspended in the box, the muslin brushed over with the solution

of aniline, and live steam allowed to pass through the gutter for only two

minutes, whereby the aniline being vaporized acts on the chromic salt and

develops the image; then the steam is allowed in the coil, and, in from

three to four minutes, the paper is dry and the picture finished. The

image stands on a slightly greenish ground, which is not objectionable for

the purpose the reproductions are made.



The sensitizing solution is similar to that published by Mr. Endemann,

viz.:



Potassium bichromate   460 grams

Sodium chloride        460 grams

Ammonium vanadate      0.75 gram

Sulphuric acid         1 liter

Water                  13 liters











THE PRIMULINE OR DIAZOTYPE PROCESS.





Primuline, discovered in 1887 by Mr. A. G. Green, an English chemist, is a

dye of a primrose color, possessing a great affinity for cotton fibers, to

which it is readily fixed by simply immersing the material for a few

moments in a hot solution of the dye.  If the material so dyed be placed

in an acidified solution of nitrous oxide, the primuline is diazotized,

forming a derivative compound of a deeper color, which fades in the light,

and which in presence of amines and phenols gives rise to a variety of

dyes whose color depends on the reagent employed, while, when acted on by

light, the resulting compound is entirely deprived of this property.  In

other words, the diazotized primuline acts as a mordant only when not

altered by the luminous action.



The chemical change light effects in the diazotized primuline is not well

known.  It is pretty certain, however, that nitrogen is set free, for if

gelatine imbued with primuline be immersed in water after insulation,

nitrogen is set free and can be collected as usual in a tub filled with

water and inverted on the substance.



By itself diazotized primuline is slowly influenced by light, but quickly

acted on in presence of organic substances.  It is more sensitive when

applied on cotton or paper than on wool, silk, linen, and such organic

compounds as gelatine, albumen, caseine, starch, etc.  Its sensitiveness

is about one-tenth less with gelatine than with cotton.



The sensitiveness of diazotized primuline to light, when united to organic

substances and the different colors which can be obtained with the

unaltered compound, have given rise to an interesting printing method, the

invention of Messrs. A. G. Green, C. F. Cross, and E. J. Bevan, which

yields _positive impressions from positive cliches_.  The manipulations of

the process are simple:



In a certain quantity of rain water, kept at nearly the boiling

temperature by an alcohol lamp placed under the vessel, dissolve per cent.

2 parts of commercial primuline, and in this immerse, by means of a glass

rod, some pieces of calico--free from dressing--turning them over several

times during the immersion.  When the fibers are well imbued, which

requires from four to five minutes, remove the calico with the glass rod

and rinse it thoroughly in water.  This done, wring out the superfluous

liquid as much as possible, and, finally, immerse each piece separately in

a solution of



Sodium nitrite,      7 parts

commercial

Hydrochloric acid,   16  parts

commercial

Water                100 parts



After turning the pieces of calico two or three times over, they are

rinsed to eliminate the acid, then drained and placed between sheets of

blotting paper to dry.  All this, except the impregnation with primuline,

should be done in the dark room.



As said above, primuline is transformed by nitrous oxide into a diazotized

compound, and consequently the material is now susceptible of being acted

on by light.  It does not keep, and should be exposed, etc., soon after

its preparation.



Paper is impregnated with primuline either by floating or brushing.  The

best results are obtained with paper previously sized with arrowroot or

gelatine in order to keep the image entirely on the surface of the paper.



Linen, silk and wool are treated as calico.



The cliches should be positive to obtain positive expressions and somewhat

more opaque than those employed in the processes before described, else

vigor and intensity could not be obtained.  Here we must state that the

primuline process seems to be better adapted for the reproductions of

drawings, such as made for the black process, and of opaque photo-cliches

in lines, or white and black, than for printing in half tone.



When the material to print upon is thick and wholly impregnated with

diazotized primuline, it is advisable, since the insulation could not be

prolonged to effect the change through, to expose the back of the material

for a certain but short period in order to _clear_ it.  This is especially

advantageous when the cliche is not of good intensity.



During the exposure, which varies from 30 seconds to 10 minutes and more

by a dull light, the progresses of the luminous action is seen by the

bleaching of the material which assumes a dingy coloration.  But in order

to ascertain when the decomposition is complete on the ground of the

image, it is well to use _tests_ as in the cyanofer process, dipping one

of them in the developer from time to time.



The developers are compounded as follows:



         FOR RED.

Beta-naphthol     4 parts

Caustic potassa   6 parts

Water             500 parts



Rub the alkali and the naphthol with a little water in a mortar and add

the remainder of the water.



    FOR ORANGE.

Resorcin   3 parts

Water      500 parts



When dissolved add



Caustic potassa   5 parts



          FOR YELLOW.

Carbolic acid, cryst   5 parts

Water                  500 parts



          FOR PURPLE.

Naphthylamine           6 parts

Hydrochloric acid, in   6 parts

volume



Mix in a mortar, then add



Water   500 parts



             FOR BLACK.

Eikonogen, white crystals   6 parts

Water                       500 parts



Pulverize the eikonogen, add the water and, at the same time, the material

on its removal from the printing frame, and keep in motion until the

development is effected.



      FOR BROWN.

Pyrogallol   5 parts

Water        500 parts



After the development, which requires but a few moments, it suffices to

wash the material to fix the image by eliminating the soluble compounds.

However, for purple the material should be passed in a dilute solution of

tartaric acid and not washed afterwards; it should remain acid.



When it is desirable to obtain an impression in several colors, the

various developers are thickened with starch, then locally applied with a

brush on the image, which is always visible after exposure.



For printing on wood, glass and porcelain, see further on.











            PRINTING ON WOOD, CANVAS, OPAL, AND TRANSPARENCIES





_Printing on Wood._--To print on a wood block a design to be engraved on

the same presents certain difficulties.  In the first place, the

sensitizing solution must not be absorbed by the wood, but remain wholly

on its surface; then the photo film, although thick enough to produce an

image sufficiently intense to be distinctly visible in all its details,

should not scale or clip away under the graver, and not interfere in any

way with the work of the artist; the least touch of the graver must reach

the wood and make its impression.  Lastly, the design should be permanent.

These difficulties will be avoided by adhering to the instructions given

in the lines following.



The solution to render impervious the surface of the wood consists of



Common gelatine   5 parts

Gum arabic        3 parts

Castile soap      3 parts

Water             100 parts



Dissolve by heat on a water bath.



To apply it, the wood is rubbed with fine sandpaper, then heated over a

spirit lamp to about 86 deg. Fahr. (30 deg. C.) and upon it is poured in

excess the liquefied and quite warm solution, which must be allowed to

penetrate in the pores of the wood by letting it gelatinize, when it is

wiped off clean.  Nothing must remain on the surface of the wood. This

done, and while still damp, the preparation is rendered insoluble by

pouring over a solution of alum at 5 per 100 of water.  The object of this

preliminary operation is to render the wood impervious, and therefore to

prevent the sensitizing solution to penetrate its texture.  The wood is

then heated again and its surface whitened with a little silver white or

sulphate of barium, diffused in a small quantity of the following warm

solution:



Gelatine   1 parts

Alum       0.1 part

Water      100 parts



While wet, this is smoothed with a jeweler's brush, taking care to leave

on the wood, a very thin layer of the mixture, only sufficient to obtain a

white surface which, by contrasting with color of the wood assists the

engraver in his work.  The wood should now be allowed to dry thoroughly,

when it is coated with a tepid solution of



Isinglass   3 parts

Water       100 parts



and dried.



Now the sensitizing process differs according as whether the cliche is

positive or negative.  In the former case the preparation is sensitized

with the solution employed in the black process, proceeding afterwards as

usual; in the latter, that is, when the cliche is negative, the best

process is the cuprotype.(12)



For printing, special frames are employed to permit one to examine the

progress of the impression from time to time without the possibility of

either the wood block or the cliche moving.  These frames open in two.

The upper frame is provided with screws on the four sides to hold firmly

the block when it is placed into contact with the cliche by means of the

screws fixed on the cross bars.  As to the cliche, if it is made on a

glass plate, it is secured on the thick glass plate of the lower frame by

two wooden bars against it pushed by screws.



When the block is ready for printing, the prepared side is usually

concave.   It is straightened by slightly wetting the back and resting it

on one end, prepared side against the wall.



_Printing on Canvas.--_The canvas should be first brushed with a solution

of aqueous ammonia in alcohol, 1:3, to remove greasiness until the thread

just commences to show, then, when rinsed and dry, rubbed with fine sand

to give a tooth, dusted, washed with a sponge and then coated with the

following solution, proceeding afterwards as in the cuprotype process:



Isinglass        8 parts

Uranic nitrate   5 parts

Copper nitrate   2 parts

Water            200 parts



_Printing on Opal, Celluloid, etc._, is quite simple; it suffices to coat

the material with the following gelatine solution, and, when the film is

dry, to proceed in operating by any one of the processes before described.



The sensitizing compound may be incorporated to the gelatine solution, but

we prefer not to do it and to sensitize the plates as they are wanted for

use.



A.   Gelatine   4 parts

     Water      70 parts in volume



Dissolve and mix little by little in order:



B.   Chrome alum   0.25 parts

     Water, hot    20 parts

C.   Alcohol       10 parts



When coated place the plates on a level stand until the gelatine is set,

and let them dry on a rack.



_Transparencies._--Prepare the plate as directed above with



A.   Gelatine      6 parts

     Water         70 parts

B.   Chrome alum   0.3 part

     Water, hot    20 parts

C.   Alcohol       10 parts



Sensitize with the uranic-copper solution employed in the cuprotype.  By

this process transparencies of a rich brown, not actinic, color are

obtained.  Consequently they can be used to reproduce negatives by the

same process.  For lantern slides they may be toned black by platinic

chloride.



To strip off the picture, apply, first, on the glass plate a substratum of

India rubber, 2 to 100 of benzole, coat with plain collodion, immerse the

plate in water as soon as the film is set, and when greasiness has

disappeared pour on the gelatine solution and proceed.



For tranferring on any material, a sheet of paper is immersed in a

solution of India rubber cement in 20 parts of benzole, dried, coated with

the gelatine solution, sensitized, etc., by operating in the ordinary

manner.  After development, the proof, being dry, is brushed over with

alumed gelatine moderately warm, dried, immersed in tepid water until the

gelatine is softened and tacky, when it is placed on the material and

squeezed into contact.  This done, the transfer should be allowed to dry

thoroughly.  Now, by imbuing the proof with benzole to dissolve the India

rubber, the paper is easily stripped off, leaving behind the picture

adhering to the material.











TRACING PROCESS ON METAL.





We call the attention of metal engravers to this process.  It is well

known that wood engravers have their original designs photographed on the

block in order to save considerable time by not making the drawing

themselves; moreover the cost is nominal, so to say, and the copy more

true and perfect than it can be done by hand.  Why should not the copper

engraver and the aquafortist avail themselves of the same advantages?  A

few do it secretly, no doubt, but the generality not knowing the process,

or, if so, not having tried it, think it is not possible or that it may

spoil their plates.  This is an error.  It can be done and very easily by

adhering to the following instructions:



Dissolve 2 parts of ammonium bichromate in 100 parts of water, and in this

let soak for an hour or so 10 parts of Coignet's best gelatine, then

dissolve on a water bath, filter through flannel, and the solution is

ready for use.



Before being coated, the plate should necessarily be cleaned free from

oxidation and greasy matters.  This is done by immersing the plate for a

few moments in a warm solution of common potash, then rinsing and rubbing

it with chalk moistened with a little water, when after rinsing again and

draining the plate should be immediately prepared.



To spread the gelatine solution in an even and thin layer, a tournette is

employed.  The most simple consists of a round wooden stick of which the

upper part is carved in the form of a cup with an edge, or rim, about one

quarter of an inch broad.  On this rim is melted some gutta-percha, upon

which the plate is pressed into contact and adhers quite firmly when the

gutta-percha is solidified.  The stick is perforated at the lower end and

revolves on an iron pivot fixed at the bottom of the support, being held

in the opening on the platform of the same, as shown in the diagram on the

following page.



The plate being fastened to the tournette, the warm gelatine solution is

flowed over it and spread to the edges by means of a glass rod or a piece

of cardboard, avoiding air bubbles.  This done the tournette is set into

motion, and when the film is equalized, which is done in a moment, the

plate is detached, placed on a leveled stand and slowly dried with the

spirit lamp.



                              [A Tournette]



By a good light the exposure on the shade does not exceed twenty minutes

with a pretty intense transparency, and should be regulated with a

photometer.  When the insulation is sufficient, the image is slightly

visible, and should be so.  The plate is then bordered with banking wax

and bitten-in with a solution of ferric chloride at 45 deg. Baume, or--



Ferric chloride, crystal   20 parts

Hydrochloric acid          1 part

Water                      100 parts



The parts of the gelatine film the most acted on are impermeable, so to

say, and consequently do not allow the etching fluid to penetrate to the

copper; while those the least impressed are permeated according as to

their degree of insolation, Therefore, when the ferric chloride solution

is poured upon the film and carefelly brushed over with a soft brush, in a

few moments the image progressively appears, the deep blacks first, then

the half tints, and lastly the most delicate details, the whole requiring

but a few minutes. It is now that the etching action should be stopped by

washing under the tap.  However, should by excess of exposure, or any

other cause, the details not appear within five or six minutes, the ferric

chloride should nevertheless be washed off, for then it may find its way

under the film and the plate would be spoiled.  After washing the gelatine

is dissolved in a solution of potash, etc., when the image would be found

slightly engraved.



Should the image be in half-tints, it would be advisable to apply a grain

of rosin on the gelatine film just before etching.  To engrave on steel

the operations are the same, but on its removal from the printing frame

the plate should be soaked with water renewed several times until the

bichromate is washed off.  The film is then dried spontaneously and

afterwards flowed for about two minutes with the Solution A, then, this

being thrown away, with the Solution B, which is allowed to act for a

similar period.



A.   Nitric acid, pure   120 parts

     Silver nitrate      6 parts

     Alcohol, 95 deg     50 parts

     Water               75 parts

B.   Nitric acid, pure   5 parts

     Alcohol, 95 deg     40 parts

     Water               60 parts











GRAPHOTYPY.





This process consists in converting a cliche in half tones into one in

lines, which can be directly printed on paper, or impressed, by means of

an ink transfer made as explained before, on a stone, or on a zinc or

copper plate for etching in relief, or in intaglio, according as the

cliche is negative or positive.



A cliche on gelatine, but preferably on a collodion film, is varnished

with a solution of yellow wax and bitumen in benzole and turpentine-oil:



Bitumen of Judaea   8 parts

Yellow wax          2 parts

Benzole             40 parts

Turpentine oil      60 parts (filter)



then etched as done to engrave in the aquafortis manner, the corrections

being made by applying with a brush some of the above varnish on the

defective parts, which are worked over when the varnish is dry.



The tools are simply needles of various thickness ground in sharp square

and round points of different sizes.



When the etching is finished, the parts which should form the ground, or

white parts of the design, being covered with the bitumen varnish is

non-actinic, or, in other words, does not admit the light acting on the

sensitive plate preparation employed to reproduce the design, except by an

exposure a good deal longer than that necessary to reduce the metallic

salts.



The engraver will see at once that, although it greatly simplifies the

copying work and, consequently, saves much time, this process does not,

however, bind him to any rules and leaves him perfectly free to follow its

inspirations and make such alterations as he thinks proper to produce

artistic effects; in a word, the reproduction will no more be a picture

taken by a mechanical process, so to say, but an original drawing

reflecting his talent and characteristic manner.



A similar process much employed by photo engravers, and presenting the

same advantages, is to convert an ordinary photograph on paper--or a blue

print, as devised by the writer--into a design in lines by drawing with

India ink, or the special ink of Higgins, and, this done, to wash off the

photographic image, the design being afterwards reproduced by the ordinary

processes as a negative or a positive cliche.



When the photograph is a silver print especially made for the purpose in

question and, consequently not _toned,_ but simply fixed in a new

thiosulphate (hyposulphite) bath, and well washed--it is bleached by

flowing over a solution of--



Bichloride of mercury   5 parts

Alcohol                 40 parts(13)

Water                   100 parts



If the photograph has been toned, i.e., colored by a deposit of gold, or

if it was fixed in a thiosulphate bath in which toned prints have been

fixed, then the image is dissolved by treatment in a solution of potassium

cyanide in alcoholized water.



When a blue photograph is reduced, it is advisable before drawing upon it

to first reduce its intensity by a prolonged immersion into water.  Pale

blue is a very actinic color which is not reproduced in photography,

except by the ortho-chromatic process, or if it does, the impression being

very weak, is not objectionable.  When the image has not been sufficiently

or not at all bleached, the blue is dissolved by an alcoholized solution

of the blue solving.











THE URANOTYPE.





This process, devised by J. Wothly, in 1864, did not receive from the

photographers the attention it merits, as it is always the case when a

process is patented, and can be replaced by another equally practical

which is not.  It gives pictures of a very good tone, which are quite

permanent; we have some made in 1866, which are suffered no change

whatever, they seem to have been printed from yesterday.



The first process given by Wothly does not appear to be complete.  It has

been well described by H. Cooper and a gentleman who signs by the initial

letter X.



The process published in 1865 by Wothly is as follows: A sheet of paper is

sized by brushing with a paste made of 24 parts of arrowroot in 500 parts

of water, to which are added a few drops of a solution of citric or

tartaric acid, then coated with a collodion consisting of 100 cubic

centimeters of plain collodion, a few drops of oil of turpentine and 30

cubic centimeters of the following sensitizing solution:



Nitrate of uranium     30 to 90 parts

Chloride of platinum   2 parts

Alcohol                180 parts



The time of exposure is about that required for paper prepared with silver

chloride.  The image is bluish-black but weak.  After washing the print is

immersed in a solution containing 0.5 parts of chloride of gold for 2,000

parts of distilled water, and then fixed in a bath of sulphocyanate of

potassium, which tones the image blue-black.



It may happen that the proof is slightly tinted red. This arises from a

small quantity of lime in the paper which forms uranate of calcium.



To prevent the proofs turning yellow, it should be washed in an

exceedingly weak solution of acetic acid.



If, after exposure, the print is immersed, without it being washed, in the

gold bath, the image becomes rose-red, but the whites remain pure. The

effect is peculiar.









                       H. COOPER'S PROCESS (1865).





     PREPARATION OF THE PAPER

St. Vincent arrowroot   200 grains

Boiling water           10 ounces



Crush the arrowroot to fine powder, then rub it to a paste with a little

water, and let an assistant pour a few drams of boiling water while you

keep stirring all the time; finally, let him add the rest of the boiling

water, the operator still continuing the stirring.  The paste is allowed

to cool, and will be thicker when cold than when hot.  Remove the upper

portion entirely when quite cold, otherwise, if any left, it will give

rise to streaks.  The author insists upon the necessity of all these

cares.  Two sheets of paper are now placed side by side on a flat board,

then the surface of the first is covered with the paste by means of a

sponge, proceeding, before you leave it, all over the sheet in a

horizontal direction; the second sheet is covered in a like manner.  By

the time the second sheet is pasted, the first one will be partially dry.

The sponge is now drawn over each sheet, in succession, in a perpendicular

direction in order to efface the streaks from the first sponging.  If the

paste drags in a slimy manner, it is too strong, and a fresh arrowroot

must be prepared, because dilution only ends in failure.  Why dry, the

paper is rolled under moderate pressure, and when it lies smoothly the

maximum pressure may be applied.



   PLAIN COLLODION.

Alcohol      12 ounces

Ether        4 ounces

Pyroxyline   80 grains



       SENSITIVE COLLODION.

Plain collodion            1 ounce

Nitrate of uranium, pure   30 grains

Nitrate or silver          5 grains



Add the uranium first, and as soon as it has dissolved all that it can,

add a grain or two of soda, and when settled pour off the supernatant

collodion and add the silver.(14) To coat the paper with collodion, use a

board with a handle beneath, such as is used by plasterers.  On this place

a sheet of paper, the edges being turned up about the sixteenth of an

inch; this enables the whole of the sheet to be covered without spilling

the collodion or allowing it to run on the back of the paper.



There is a marked difference in the appearance of the prints when they

leave the pressure frame. Some samples of collodion cause the picture to

print of a beautiful green, others of a rich brown, and some of a yellow

or orange tint.  The last take the longest of all to tone, and difficultly

assume the tint of well toned silver prints,(15) those printing to green

or brown tone very rapidly.



After printing the pictures are placed in diluted sulphuric acid, 1 to 30

of water, until the high lights are perfectly clear and white; this takes

from ten to fifteen minutes.  After washing well under a stream of water,

they are placed in the toning and fixing bath.



         TONING AND FIXING BATH.

Sulphocyanide of ammonium   1 ounce

Water                       12 ounces

Chloride of gold            1 to 3 grains



After removing from this bath, the prints are immersed for a few moments

in water, and then rapidly washed.



    FORMULA FOR PREPARING THE PYROXYLINE

Nitric acid, sp. gr. 1.30   12 fluid ounces

Sulphuric acid, sp. gr.     36 fluid ounces

1.845

Water                       8 fluid ounces

Temperature                 130 degrees Fahr.

Time of immersion           15 minutes.









              X'S PROCESS (1865). (Secrets of the Uranotype)





_Preparation of the Uranium Compound.--_Precipitate the nitrate of uranium

from its solution by concentrated liquid ammonia.  Let settle the

precipitate, decant, and wash in several changes of water.  Dissolve it by

heat in pure nitric acid, _taking care not to add an excess of acid._  The

ammonio-nitrate of uranium salt is then crystallized and dried.  Mix a

solution of 6 drams of this salt, dissolved in 3 drams of water, to a

solution of 15 grains of silver in 30 minims of water, and crystallize.

This salt is called _ammonio-nitrate of uranium and silver._



     SENSITIZING SOLUTION.

Ammonio nitrate salt   3 drams

Alcohol                8 drams

Distilled water        15 drops

Nitric acid, pure      1 drop



_Plain Collodion.--_Dissolve in a small quantity of ether 1 dram of Canada

balsam and 1 dram of castor oil, filter and let evaporate the solution to

the consistency of oil.



Of this, add 10 minims to a collodion made of



Alcohol      10 ounces

Ether        20 ounces

Pyroxyline   220 grains



         SENSITIVE COLLODION

Plain collodion        12 drams

Sensitizing solution   6 drams

Nitric acid            2 or more drops



Keep this collodion in the dark, as it is quite sensitive.



     PREPARATION OF THE PAPER

Arrowroot, pulverized    1 ounce

Water                    32 ounces

Solution of acetate of   10 drops

lead



Heat to 100 deg. Fahr. and then add four ounces of albumen.  The paper is

floated on this solution for five minutes and hung up to dry.  The sizing

may also be applied with a sponge in the manner often described.



The proofs should be slightly over-printed and, before toning and fixing,

placed for about ten minutes in the following solution:



Distilled water     40 ounces

Acetic acid         1 ounce

Hydrochloric acid   1 ounce



After washing in several changes of water, the proofs may be toned in any

toning bath, and then fixed with sulphocyanide of potassium, washing

afterwards in the usual manner.











THE PLATINOTYPE.









This process, discovered by William Willis,(16) yields very fine

impressions which wholly consists of platinum and are, therefore,

chemically permanent.  It has been described theoretically and practically

by Pizzighelli and Kuebl in a paper for which the Vienna Photographic

Society has awarded the Voightlander prize.(17) The following is an

abridgment of this important process, as described by the authors:



The paper, calendered or not,(18) is sized with gelatine or arrowroot.

The color of the proof with the latter size is brownish black, and bluish

black with the former.



To prepare the gelatine solution 10 parts of gelatine are soaked in 800

parts of water and then dissolved at a temperature of 60 deg. C. (140 deg.

Fahr.), when 200 parts of alcohol and 3 parts of alum are added and the

solution filtered.



To prepare the arrowroot solution 10 parts of the substance are powdered

in a mortar with a little water and mixed to 800 parts of boiling water,

added gradually in stirring.  After boiling for a few minutes 200 parts of

alcohol are added and the mixture filtered.



These solutions are employed warm.  The paper is immersed for two or three

minutes and hung up to dry in a heated room, then immersed a second time

and dried by hanging it up in the opposite direction, in order to obtain

an even coating.



The potassic platinic chloride is an article of commerce.  It should be

soluble without residue in 6 parts of water and without acid reaction.  In

this proportion it constitutes the normal stock solution employed in the

various formulas.



The standard ferric oxalate solution is also found in commerce. Treated by

potassium ferricyanate it should not be colored blue, nor become turpid

when diluted with one-tenth part of water and boiled.  The former reaction

indicates that it contains no ferrous salt, and the latter no basic

oxalate.



The authors give the following instructions for preparing the ferric

oxalate solution, to which they attach much importance:



Five hundred parts of ferric chloride are dissolved in 5,000 parts of

water and heated to boiling, when a solution of soda is added until the

liquid becomes alkaline.(19) About 250 parts of caustic soda are generally

employed for this purpose.  The precipitate--ferric oxide--is now washed in

warm water until the last washing water is quite neutral to test paper,

then drained and mixed with 200 parts of pure crystallized oxalic acid.

The mixture is then allowed to stand in the dark for several days at a

temperature not exceeding 30 deg. C. (86 deg. Fahr.)  At first the

solution from green turns to a yellow green, and finally becomes almost

brown.  At this moment the excess of ferric oxide is filtered out and the

liquor submitted to a quantitative analysis, the result of which leads to

ascertain the quantity of ferric oxalate in 100 parts of the solution and

the excess of oxalic acid.  The solution should then be diluted with

distilled water, such as it contains 20 parts of ferric oxalate per 100

parts of water, and oxalic acid must be added in the proportion of from 6

to 8 per 100 of the ferric oxalate, taking into account the quantity of

acid the solution already contains.  The solution should be kept in the

dark.  It is altered by light.(20)



       IRON CHLORATE SOLUTION

Ferric oxalate solution   100  parts

Potassium chlorate        0.4 parts



This solution is employed to obtain more contrasts.



  PREPARATION OF THE SENSITIZING SOLUTION

Platinum solution         12 parts

Ferric oxalate solution   11 parts

Distilled water           2 parts



This solution gives very soft tones with intense black.  To obtain more

brilliancy we use the following proportions:



Platinum solution           12 parts

Ferric oxalate solution     9 parts

Chlorate of iron solution   3 parts

Distilled water             2 parts



To obtain results comparable to those which the silver printing out

process gives, the following mixture is employed:



Platinum solution           12 parts

Ferric oxalate solution     8 parts

Chlorate of iron solution   4 parts

Distilled water             8 parts



For very weak negatives, reproductions of drawings, etc., we use--



Platinum solution   12 parts

Chlorate of iron    11 parts

Distilled water     2 parts(21)



To obtain proofs not completely black, as, for example, reproductions of

lead drawings, the solution may be diluted with half or the whole volume

of distilled water.  But if the solution be applied on little absorbent

surfaces or on paper strongly sized it is not advisable to dilute it.



_Preparation, of the Paper.--_The paper should be kept slightly moist in

order that it does not too completely absorb the sensitizing solution.

Therefore, when the atmosphere is very dry, it is well to keep the paper

in a damp place, in the cellar for example.  Before sensitizing, which

should be done by a very diffused light, a quantity of the solution

proportionate to the surface to be sensitized (about 15 c.c., for a whole

sheet of Rives' or Saxe paper) must be measured, and spread with a large

brush(22) on the paper fixed with drawing pins on a board covered with a

sheet of blotting paper.  When well impregnated, the paper is hung up to

dry in the dark room, and as soon as the apparent dampness of the surface

has disappeared, it should be dried immediately at a temperature of 30--40

deg. C. (86--101 deg. Fahr).  If the paper be dried too rapidly the

sensitive compound remains on its surface, and in developing the image

does not come out well.  If, on the other hand, the drying is too slow,

the solution penetrates too much in the paper and the image is wanting of

vigor and does not appear very sharp.  One cannot depart from this rule

that the desiccation from the moment the solution has been applied until

the paper is dry should last no more than from twelve to fifteen minutes.



The sensitized paper is hygroscopic and must be preserved in a calcium

box.  _It is a conditio sine qua non that the paper must be quite dry

before, during, and after printing, to obtain good results._  Dampness is

the greatest enemy in this process.



For printing a pad of India rubber should be placed over the platinum

paper to prevent it from attracting the atmospheric moisture, and in damp

weather it is even advisable to cover it with several sheets of blotting

paper previously heated before the fire.



The platinum paper is at least three times more sensitive than the silver

paper used in the printing-out process, under the reductive action of

light the yellow color of the prepared paper turns brown and then becomes

of a lighter color, nearly orange, so that the darker parts of the image

often appears more luminous than the dark half tints.  No rule can be

given to regulate the insolation, but after a few trials it is easy to

judge when it is right by observing the progress of the reduction and the

color of the image. The orange color indicates the complete reduction of

the ferric oxalate.  When the details in the lights are _faintly_ visible,

the exposure is generally right.



The developer consists of an almost saturated solution of potassium

oxalate _acidified by oxalic acid,_ and for use heated to 80--85 deg. 0.

(176--184 deg. Fahr.),(23) in an agate glazed iron tray placed upon a water

bath at the above temperature. By simply drawing the proof over it, the

image is at once developed.(24)



When the proof is thought to be over-exposed, the oxalate solution can be

employed at a lower temperature.  If, on the contrary, it is

under-exposed, the solution may be heated even to the boiling point.



The developer can be used over and over again.  _It should always have an

acid reaction._



According to Mr. Borlinetto a sepia tone is obtained by using the

following cold developer:



Saturated solution of   120   parts

potassium oxalate

Saturated solution of   13   parts

copper chloride

Oxalic acid             1.5 part



After developing the proofs are _immediately_ immersed for fixing in a

solution of hydrochloric acid, 1 to 80 of water, renewed so long as the

paper is tinged yellow (about three times), leaving the proofs ten minutes

in each solution.  Lastly, they are washed to remove the acid.



The platinotype has been still improved by Captain Pizzighelli, who

devised the following methods of operating by which the impressions are

obtained by the continuous action of light, that is, without development,

thus rendering the platinotype just as simple as the ordinary printing-out

silver process.



In these new processes to the sensitizing solution is added the alkaline

oxalate, which effects the reduction of the platinous salt during the

exposure to light.  Consequently the prepared paper is insolated until the

image appears as it should be, or--which is exceedingly useful in cloudy

weather--until it is entirely visible but still deficient in delicate half

tones, for in the dark the action proceeds and the image developing itself

will be found finished in a period which may extend to a few hours.  But

it can be, however, developed in a few seconds by immersion in a cold or

slightly warm solution of sodium carbonate, 1:25 of water. The image is

fixed as directed in the foregoing process.



The paper, prepared exactly as in the former process and kept in the

calcium box until wanted for use, should not be employed quite dry, but

allowed to absorb a little moisture by hanging it in the dark room.

Hence, the India rubber and other protecting pads can be dispensed with.

They are even objectionable, for dampness is absolutely necessary to

promote the chemical changes by which the image is developed.



    A. AMMONIO-FERRIC OXALATE SOLUTION

Ferric oxalate solution    100 parts

Neutral ammonium oxalate   18 to 20 parts



    B. SODIO-FERRIC OXALATE SOLUTION

Ferric oxalate solution   100 parts

Neutral sodium oxalate    15 to 18 parts



To prepare these two solutions the ammonium or sodium oxalate is dissolved

by small quantities at a time, and when the emerald color due to the

formation of the double oxalate commences to darken, the saturation being

then complete, no more of either salt should be added.  The solution is

now well shaken with 3 parts of glycerine, allowed to settle and filtered.



Any one of the double oxalates can be used.  The ammonium tends to produce

softer pictures and bluish tones.  To obtain more contrasts a little

potassium chlorate may be added.



   C. IRON CHLORATE SOLUTION

Solution B           100 parts

Potassium chlorate   0.4 part



       D. MERCURIC SOLUTION.

Mercuric chloride         20 parts

solution at 5:100

Sodium oxalate solution   40 parts

at 3:100

Glycerine                 2 parts



      SENSITIZING SOLUTIONS.

         FOR BLACK TONES.

Platinite solution, 1:6   5 parts

Solution B                6 parts

Solution C                2 parts



        FOR SEPIA TONES.

Platinite solution, 1:6   5 parts

Solution C                4 parts

Solution D                4 parts



Intermediate tones are obtained by diminishing the dose of C and replacing

it by an equal volume of B.  For this process the paper should be sized

with



Arrowroot                 2 parts

Sodium oxalate at 3:100   100 parts



To dispense with this preliminary sizing Captain Pizzighelli adds gum

arabic to the platinite solution, whereby the sizing and sensitizing are

done in one operation.



The gum arabic solutions are prepared as follows:



E.   Gum arabic in       40 parts

     powder

     Sodium ferric       40 parts

     oxalate solution,

     B

     Sodium oxalate      100 parts

     solution at 3:100

     Glycerine           3 parts



Place the glycerine and the gum arabic in a mortar, then, stirring with

the pestle, dissolve by adding, little by little, the mixture, heated to

40--45 deg. C. (104--113 deg. Fahr.), of the solution of sodium ferric

oxalate and sodium oxalate.  Let stand for about two hours and grind again

to dissolve entirely the gum arabic. Filter through muslin.



F. Mercuric chloride       20 parts

solution, 5:100

Sodium oxalate solution,   40 parts

3:100

Gum arabic in powder       24 parts

Glycerine                  2 parts



Dissolve as said above.



      SENSITIZING SOLUTIONS.

         FOR BLACK TONES.

Platinite solution, 1:6   5 parts

Solution E                6 parts

Solution C                2 parts



        FOR SEPIA TONES.

Platinite solution, 1:6   5 parts

Solution C                4 parts

Solution F                4 parts



Mix just before use.  The solutions do not keep.  The paper prepared by

either one of these two processes can be exposed as in the _old_ process,

and the image developed bythe hot oxalate solution.



The preparation of wood, canvas, etc., for the platinotype printing need

not to be described; it suggests itself.









                           CAUSES OF FAILURES.





_The images are veiled._



This defect may result from various causes, viz.:



 1st. The stock ferric oxalate solution is impaired by a partial reduction

      of the ferric salt into ferrous oxalate.  The solution should be

      preserved in an orange colored vial, and kept in the closet of the

      dark room.  It should be tested from time to time for the ferrous

      salt with a solution of potassium ferricyanate.  If it does not

      contain any ferrous oxalate it can be used by adding to it a little

      of the iron chlorate solution.

  2d. The paper has been exposed to light during the sensitizing or the

      subsequent operations.  One should bear in mind that the platinum

      paper is twice more sensitive than silvered paper.

  3d. The sensitized paper has been dried at a temperature above 40 deg.

      C. (104. deg. Fahr.)

 4th. Over-exposure.



_The proofs are not sharp._



 1st. The sensitive paper has absorbed moisture.

  2d. It is too old.  The paper cannot be kept good for over six weeks,

      unless special care be taken.



According to Mr. Bory, the sensitive paper altered by keeping is restored

to its original good quality by simply brushing it over with a solution of

0.05 parts of potassium chloride or the same quantity of potassium

chlorate in 100 parts of distilled water, or a mixture of these two

solutions, or one of iron chlorate.



By treating the insolated paper with these solutions, the image is

destroyed, and the paper can be used again.  One operates as for

sensitizing, taking care to desiccate the paper, as it has been directed.



_The proofs are brilliant during the development, but become dull in

drying._



The paper not well sized. It has been dried too slowly.



Remember that it should be quite desiccated within fifteen minutes.



_The paper is more or less yellow._



 1st. The paper tinted with ultramarine.

  2d. The sensitizing solution or the developer are not sufficiently acid.

  3d. The washing (fixing) in the solution of hydrochloric acid was not

      sufficient to eliminate the iron salts from the paper.



_The proofs harsh, devoid of half tones._



 1st. The sensitizing solution contains too much iron chlorate.

  2d. Exposure too short.



_The paper is stained._



The brush not kept clean while sensitizing.



_Black spots._



They are generally due to metallic dust in the paste of the paper, or from

particles of undissolved salt in the platinite solution.



NB: No good results can be expected unless the paper be kept absolutely

dry before, during and after exposure, when using the former (original)

process.



Impaired sensitiveness of the paper, want of vigor, tinged whites,

muddiness, indicate dampness.









ARTIGUES' PROCESS





The Artigues process, so called, is, without any doubt, the best to be

employed for the reproduction of plans and drawings in lines.  It is

simple, expeditious, and yields black impressions on a very pure white

ground which are absolutely permanent.  And this is of the utmost

importance when the copies are to be used for military purpose, or kept in

archives, such as those of the Patent Office, for example.  Should it not

require the use of negative cliches, it would certainly supersede any of

the processes previously described; moreover, as it will be seen, it can

be employed for many other purposes than that of obtaining duplicates from

original drawings.  The objection is not even very great indeed, for the

design can be, without great trouble, transformed into a negative by the

aniline method described in the beginning of this work.



The Artigues process is an adaptation for the purposes in question of the

carbon process invented by Poitevin.  We shall describe it in extenso.



The paper can be prepared with any one of the following solutions:



 1st. Dissolve 21/2 parts of ammonium bichromate and 5 parts of best gum

      arabic in 15 parts of water and neutralize with a few drops of

      concentrated aqueous ammonia; then add 100 parts in volume of whites

      of egg and a certain quantity of thick India ink, and, this done,

      beat the whole to a thick froth.  In ten or twelve hours the albumen

      will be deposited and ready for use.



      The quantity of India ink added to the albumen should be such as the

      paper be black when coated, but, however, sufficiently transparent

      for one to see the shadow of objects placed on the back of it, and

      the coating should not be thick.  This is important in order to

      allow the light acting through the whole thickness of the

      preparation when the paper is insolated under the cliche, for, if

      the film be too opaque or too thick (by addition of too much gum

      arabic), it would be only impressed on its surface, and the image

      dissolved during the development.  The cause of this failure must be

      explained.  Under the action of light the bichromate employed to

      sensitize the albumen is reduced into chromic oxide which render

      insoluble this organic substance--or any other, such as caseine,

      gelatine, gum arabic, etc.; therefore whenever the film is not acted

      on in its whole thickness, the subjacent part being still soluble,

      is necessary washed off and with it the superficial impressed part,

      that is, the image.



  2d. Take 10 parts of lamp black and work it up in a mortar to the

      consistency of a thin paste by gradually pouring a little of a

      solution of from 6 to 8 parts of gum arabic and 1 part of liquid

      glucose in 100 parts of water, adding afterwards the remainder, into

      which 21/2 parts of ammonium bichromate have been dissolved, and

      filter through flannel.  With this, coat the paper by brushing so as

      to form a thin and uniform film, and pin it up to dry in the dark.



These solutions keep well for a certain period.  We have kept the albumen,

which we prefer to use, for two months in good condition; but the

sensitive paper does not for more than three or four days in taking the

usual care.  It is more practical--and this is recommended--to leave out the

bichromate from the preparations, and to coat the paper, in quantity,

beforehand, and for use to sensitize it with a solution of potassium

bichromate at 31/2 per cent. of water applied on the verso with a Buckle

brush.(25)



The bichromate solution should be allowed to imbue the paper for about one

minute, and having brushed it once more, the paper is pinned up to dry in

the dark room.  It can also be sensitized from the back by floating, if

this manner is found more convenient.



When dry the paper is impressed under a negative cliche of good intensity

until the design, well defined in all its details, is visible on the back

of the paper, which requires an insolation of about two minutes in clear

sunshine, and from eight to ten times longer in the shade.  In cloudy

weather the exposure to light is necessarily very long.



As explained before, the luminous action, by reducing the chromic salt in

presence of certain organic substances, causes the latter to become

insoluble; consequently if, on its removal from the printing frame, the

proof be soaked in cold water, for, say, ten minutes, and, placing it on a

glass plate or a smooth board, gently rubbed with a brush or a soft rag,

the parts of the albumen or gum arabic preparation not acted on will

dissolve, leaving behind the black image standing out on the white ground

of the paper.  This done, and when the unreduced bichromate is washed out

in two changes of water, the operation is at an end.



As to the theory of this and similar processes, the insolubilization of

the bichromate organic substance acted on by light was formerly attributed

to the oxidation of the substance by the oxygen evolved during the

reduction of the chromic salt into chromic oxide; but from the fact that

oxidation generally tends to destroy organic matters, or to increase their

solubility, it is more probable that it results from the formation of a

peculiar compound of the substance with chromic oxide (J. W. Swan);

moreover, gelatine imbued with an alkaline bichromate, then immersed first

in a solution of ferrous sulphate and afterwards in hot water, is

insolubilized with formation of chromium trioxide, Cr2O7K2+SO4Fe =

SO4K2+C2O4Fe+C2O3 (Monckhoven).  A similar but inverse action occurs, as

shown by Poitevin, when gelatine rendered insoluble by ferric chloride

becomes soluble by the transformation, under the influence of light, of

the ferric salt into one at the minimum.



The writer has improved the above process by simplifying the modus

operandi as follows:



Instead of compounding the preparation with gum arabic and the coloring

matter, the albumen is simply clarified by beating the whites of eggs to a

froth, etc., and the paper is coated by floating for one minute, then hung

up to dry in a place free from dust.



If the reader has any objection for albumenizing his own paper, he can use

the albumen paper found in the market for the printing-out silver process

generally employed by photographers.



The paper is sensitized from the back with the potassium bichromate bath

by floating or by brushing.  When dry, it is exposed as usual, but for a

shorter period than when the preparation contains the India ink or other

coloring matters which impede the action of light.



The progress of the impression is followed by viewing, from time to time,

the albumenized side of the paper.  When the design is visible, well

defined and brownish, the proof, being removed from the printing frame, is

rubbed with very finely powdered, or, better, levigated graphite, and,

this done, immersed in cold water for from fifteen to twenty minutes, when

by gently rubbing it under a jet of water with a soft rag, or with a

sponge imbued with water, the albumen is washed off from the parts not

acted on, leaving the design on a perfectly white ground.



If instead of graphite, or any dry color insoluble in water, lithographic

ink, much thinned with turpentine oil, be applied on the print in a light

coating which permits one to see the design under it, and if, then, the

print be soaked in water and afterwards developed as just directed, an

image in greasy ink is obtained.  And, furthermore, by replacing the

printing by transfer ink, one readily obtains a transfer ready for the

stone or a zinc plate to be etched in the ordinary manner.



As usual there are two causes of failures in these processes, viz., under

and over-exposures.  In the former case the image is partly washed off; in

the latter the ground cannot be cleared.  The reasons are obvious.



Mr. de Saint Florent gives the following processes:(26) A sheet of

albumenized or gelatinized paper is sensitized from the verso on a

solution of potassium bichromate, dried in the dark and exposed under a

positive cliche.  After insolation, the proof is washed in water, to which

are added few drops of ammonia, then inked all over with an ink consisting

of 100 parts of liquid India ink, 7 parts of sulphuric acid and 3 parts of

caustic potassa, and dried in a horizontal position.  When quite dry, the

proof is placed in water, and after an immersion of about ten minutes,

rubbed with a soft brush: the image little by little appears, and if the

time of exposure be right, it is soon entirely cleared, and, then, if not

enough vigorous, it may be inked again.  The gloss of the image is removed

by means of a solution of caustic potassa at 10 per 100, and the proof

finally washed with care.



If in lieu of albumen paper, one employs paper prepared with a  thin

coating of gelatine, and dissolves the not acted on gelatine in warm

water, a very fine positive image is obtained by means of acidified inks

which will fix themselves on the bare paper.



Positive impressions from positive cliches can also be obtained in

operating in the following manner: On its removal from the printing frame

the proof is washed, sponged between sheets of blotting paper, then

covered with not acidified India ink mixed with potassium bichromate, and,

when dry, exposed from the verso to the action of light.  This done the

image is cleared with a somewhat hard brush.









THE CARBON PROCESS.





The carbon tissue is seldom prepared by photographers. However, for the

sake of completeness, we shall give the formula of the mixtures most

generally employed, and describe the manner of coating the paper on a

small scale.



_Preparation of the Tissue.--_The gelatine generally recommended to

compound the mixture is the Nelson's autotype gelatine.  Coignet's gold

label gelatine, mixed with a more soluble product, such as Cox's gelatine,

for example, gives also excellent results.



Gelatine    110 parts

Sugar       25 parts

Soap, dry   12 parts

Water       350 parts



The coloring substances consist of:



 FOR ENGRAVING BLACK.

Lamp-black     20 parts

Crimson lake   2 parts

Indigo         1 part



   FOR WARM BLACK.

Lamp-black     3 parts

Crimson lake   3 parts

Burnt amber    2 parts

Indigo         1 part



         FOR SEPIA

Lamp-black         2 parts

Sepia of Cologne   18 parts



 FOR PHOTOGRAPHIC RED BROWN.

India ink        3 parts

Crimson lake     4 parts

Van Dyck brown   4 parts



For blue, Turnbull's blue is employed; for yellow, light chrome yellow;

for red, carmine dissolved in aqueous ammonia, evaporating, then adding

water, etc. (See further on.)



To prepare the mixture, dissolve the sugar and soap in the cold water, add

the gelatine, let it soak for an hour, then dissolve it in a water bath

and mix by small quantity the colors finely ground together and wetted to

the consistency of a paste.  After filtering through flannel the mixture

is ready for use.



For coating, the method devised by Mr. Alf. Harman has been found

excellent in the hands of the writer, not only for the purpose in

question, but also for coating paper with gelatinous or viscous (gum

arabic) preparations.



"Take two tin dishes, such as used for the development of the carbon

prints; arrange one on your bench tilted to an angle; the lower angle is

intended to receive the warm water for keeping the gelatine mixture to a

proper temperature.  Into this angle of the tray arrange another tray

somewhat smaller, and keep it from touching the bottom of the outer one by

the insertion of any small article that will suggest itself. Into the

inner tray the gelatine mixture is to be poured."



"The actual making of the tissue can now be proceeded with, and is so

simple and certain as not to be believed until put to the test.  Purchase

a roll of paper-hanger's lining paper of good quality, cut it into widths

of about one and a half inch less than the width of your inner tray, and

in length of, say, thirty inches.  For the success of the operation it is

necessary that the paper be rolled up the narrow way.  Now having just

sufficient water at a temperature of 100 deg. Fahr. (38 deg. C.) into the

outer tray, pour the gelatine mixture into the inner one, and take one of

the lengths of rolled paper, and, holding it by both ends, gently lower it

on the surface of the gelatine; then at once slowly raise the end of the

paper, which will unroll itself and become beautifully coated in far less

time than it takes to describe.  Twenty sheets may be coated in a quarter

of an hour, and be equal in all respects to that made by the most

expensive machine."



In the description of this method of coating, Mr. Harman does not explain

how the gelatine should be allowed to set before hanging up the paper to

dry, which is, however, obviously important.  It is as follows: Place on

the tray a smooth board a little larger than the sheet of paper, leaving a

small space at the end furthest from the body, and slowly, without a stop,

draw off the paper, prepared side uppermost, on the board upon which it

should remain until the gelatine is set.  If the paper curls up, wet the

back a little with a sponge before coating.



The following coating method, due to Mr. Chardon, is excellent for sheets

of paper of the ordinary photographic size, 18x22 inches.



On a glass plate placed on a leveled stand, is laid a sheet of paper

previously wetted, which is then flattened into contact with an India

rubber squeegee, taking care to remove the air bubbles interposed. The

quantity of gelatine necessary to coat the paper is regulated by means of

a glass rod held by an iron lath, which serves to handle it; at each end

of the rod is inserted a piece of an India rubber tube whose thickness

regulates that of the gelatine layer. The mixture is poured from a small

teapot, at the opening of which has been adapted a bent glass tube about

three-sixteenths of an inch in diameter, between the rod and the lath, so

that by a simultaneous motion, one can equalize the gelatine as it is

poured on. When the gelatine is set the paper is hung up to dry.  In

drying, the gelatine contracts, and, necessarily, causes a deformation of

the tissue, which curls up at the edges and loses its planimetry.  To

prevent this, while the gelatine is almost dry, the tissue is placed under

pressure until quite desiccated.  Dumoulin advises to apply on the film,

while still soft and tacky, a wooden frame, which, by adhering to it.

keeps the tissue perfectly plane as it dries.



                      [Chardon's method of coating]



_Sensitizing.--_The tissue is sensitized in a bath of potassium bichromate.

The degree of concentration of the bath, which varies from 2 to 5 per

cent. of water, is important.  The tissue sensitized in a weak bath is

less rapidly acted on by light and yields more contrasts than when imbued

in a concentrated one.  The former should consequently be employed for

printing weak negatives, and the latter for those which are intense.  A

bath compounded with 30 parts of potassium bichromate, 1,000 parts of

water and 2 parts of aqueous ammonia, is used for printing negatives of

the ordinary intensity, the tissue being, then practically of the same

sensitiveness, a silvered paper insolated to obtain a print not

over-exposed.  For intense negatives the ammonia should be discarded and

replaced by the same quantity of chromic acid.



The time of immersion has also a certain influence on the results.  The

less the tissue is allowed to absorb the solution the less sensitive it

is, but also the more the tendency of the half tints to be washed off

during the development.  Generally the tissue should remain immersed until

it lies flat and the edges just commence to curl up, unless white and

black impressions are desired, but even then it is preferable to operate

as said above, using a bath at 2 per cent.



For use the bichromate bath should be cooled down to 15 deg. C. (59 deg.

Fahr.), and much lower in summer, say 10 deg. C. (50 deg. Fahr.), and kept

at about this temperature by placing pieces of ice around the tray.  At 20

deg. C. (68 deg. Fahr.) the prints are more or less granulated; above this

the gelatine is softened and the reticulation greater; at 25 deg. C. (75

deg. Fahr.) it may dissolve.



The addition of alcohol to the bichromate bath--sometimes recommended to

harden the film and allow it to stand a higher temperature, and to hasten

the desiccation of the tissue--is objectionable, for the spirits tend to

reduce the bichromate, which is transformed into the green salt, and,

therefore, a partial or complete insolubilization of the gelatine is the

result.



Aqueous ammonia added to the sensitizing solution has for its object to

permit one to keep the sensitive tissue for a somewhat longer period, but

it renders it less sensitive.  If enough be added to turn the solution

yellow weak prints are obtained.



The bichromate bath should be renewed often. It does not keep owing to the

presence of gelatine and other organic matters which it dissolves and

which cause the reduction of the chromic salt even in the dark.  The

tissue prepared in such a bath is not very sensitive and the image

develops with difficulty, and even cannot be developed at all.



As said above, the tissue is well sensitized when its edges commence to

curl up.  It is then removed from the bath by drawing it on a glass rod

fixed at the end of the tray, and placed, prepared side down, on a

slightly waxed glass plate, rubbing it with an India rubber squeegee to

remove the superflous liquid, when it is hung up to dry.



While wet the bichromated tissue is insensitive; the sensitizing can

therefore be made by daylight, but the drying should of course be done in

the dark room, that is in a room lighted by a candle or the sunlight

filtered through a deep orange window glass.



_Caution.--_The soluble bichromates are very poisonous.  By absorption they

produce skin diseases not without danger and very difficult to cure. Hence

when handling the wet tissue the fingers should be protected by India

rubber tips, and any yellow, stains on the hands should be rubbed with a

dilute solution of aqueous ammonia, and the hands well rinsed in water.



_Drying.--_When the tissue dries rapidly it adheres well on the support

upon which it is applied for developing and yields brilliant images which

are easily cleared.  On the other hand, were it allowed to dry slowly the

adherence would not be so complete, the image dull and developing with

difficulty.  They may even refuse to develop at all from the

insolubilization of the gelatine.



In winter and in the cool days of spring and autumn, the gelatine dries

quick enough in the air, but when the weather is warm and damp, the

gelatine, drying very slowly, may be so softened as to run off, or to

produce an entirely objectionable reticulation, or the defects above

mentioned.  This may be avoided by drying it pinned up in a box, or a

closet, over quick-lime.



When dry, the tissue is generally wrinkled, brittle, breaks easily in

handling and cannot be laid flat on the cliche; but by holding it over a

basin of boiling water, the steam in a few moments rendering it

sufficiently pliable to lay it flat between glass plates, where it should

be kept under pressure until wanted for use.



The writer always dries the tissue in the following manner, which he

devised about sixteen years ago.(27) And not only the least trace of

reticulation is avoided, but the tissue, drying quite flat, lies in

perfect contact with the negative, which is quite important to obtain

proofs exactly sharp all over.



A clean glass plate is rubbed with talc, or, which the writer prefers,

flowed with a solution of(28)

Yellow wax, pure   1 part

Benzine, pure      100 parts



then strongly heated, allowed to cool and rubbed clean (apparently) with a

piece of flannel.  After once more repeating this operation the plate is

coated with the following plain collodion:(29)



Ether, conc.      250 parts, in volume

Alcohol, 95 deg   250 parts, in volume

Pyroxyline        3 parts



When the film is set, the plate is immersed in filtered water until

greasiness has disappeared, when on its removal from the bichromate bath

the tissue is laid, without draining, upon it and pressed into contact

with the squeegee to remove the excess of liquid and, with it, the air

bubbles interposited.  The tissue is then allowed to dry in the air on the

collodionized plate in the cold season, or, when the weather is warm and

damp, in a box in the bottom of which is placed a quantity of quicklime in

earthen dishes.  When dry, the plates are placed one upon another, wrapped

in paper and kept in a dry place.  When wanted for use the tissue is

stripped off and will be found quite flat with a beautiful surface to

print upon.



One should avoid to keep the sensitized tissue in a moist and warm

atmosphere, for in less than ten hours it becomes insoluble even in

complete darkness.  It should neither be kept in the air contaminated with

gaseous reductive matters, such as the products of the combustion of coal

gas and petroleum, sulphydric or sulphurous emanations from any source,

the fumes of turpentine oil, etc., which, by reducing the chromic salt,

cause the insolubilization of gelatine, prevent the print to adhere on the

support or the clearing of the image, which may even refuse to develop.



The sensitive tissue keeps well for three or four weeks in cool and dry

weather, and no more than eight or ten days in summer unless well

desiccated and kept in a preservative box.  If kept too long the image

cannot be developed.



_The Photometer.--_The time of exposure is regulated by means of a

photometer.  Of all the photometers which have been devised for that

purpose we do not know any one more practical than that suggested in 1876

by Mr. J. Loeffler, of Staten Island. It is made as follows: On a strip of

a thin glass plate, 6x2 inches, make four or five negatives, 11/2x11/4 inch,

exposing each one exactly for the same period and developing in the usual

manner, but without any intensification whatever.  It is even advisable to

reduce the intensity if they were opaque.  Fix, etc., and apply a good

hard varnish.  Now cover the back of these negatives with strips of

vegetable paper or transparent celluloid, or, better, of thin sheets of

mica, in such a manner as there be one thickness on the second negative,

two on the third, three on the fourth, etc., leaving the first one

uncovered.   Then place on the whole a glass plate of the same size as the

first and border like a passe-partout.



_The Negatives.--_For the carbon process the negatives should be intenser

than those intended for printing out on silver paper.  However, good

proofs may be obtained from any negatives, so to say, by varying the

strength of the bichromate solution, as, also, by _using the tissue

freshly sensitized for weak negatives,_ in order to obtain vigor, and _for

strong negatives, the tissue two or three days after its preparation,_

when it yields better half tones.  Printing dodges are also resorted to.

That the most commonly employed consists to varnish the back of the

negatives with a matt varnish, or to stretch on the same a sheet of

mineral paper upon which the retouches are made by rubbing graphite,

chrome yellow, pink or blue colors to strengthen the shadows or the

whites, as the case requires.  As a rule, it is advantageous to cover the

printing frame with tissue paper, whatever be the quality of the

negatives.



The negatives should be bordered with deep yellow or orange-red paper to

form what is termed a "safe edge" upon which should rest the tissue in

order to prevent the margin from being insolubilized by the reductive

action of light.  If this precaution were neglected it would be impossible

to strip off the paper without tearing the proof when the tissue is

applied on the support upon which the image is to be developed.



Before exposing it is advisable to ascertain what the printing qualities

of the negative are by making on silvered paper a proof of it--_not

over-printed--_and another of the photometer, both being exposed at the

same time and for the same period.  This done, compare the proof from the

negative cliche with those of the photometer, and mark the negative with

the number of that of the photometer to which it corresponds, stating the

shade of the proof next to it; for example: _No. 2_; _No. 3 faint, or

commences to appear,_ etc.  This No. 2 and the observation will indicate

the intensity of the negative and serve as a guide for printing on the

tissue, since, as before explained, the silver paper is practically of the

same sensitiveness as the tissue prepared for negatives of the ordinary

intensity.



_Exposure.--_To print, the tissue is laid over the negative, taking care

that it covers the safe edge, and a strip of silvered paper placed in the

photometer, then both the printing frame and the photometer are exposed to

light side by side.



Unless the negative be weak, when more vigor is obtained by exposing in

sunshine, the printing should be done in the shade.  It is a well-known

fact that the part of the bichromated film corresponding to the half

tones in the lights are not sufficiently impressed in comparison to the

blacks while impressed in direct sun's light in this as well as in the

collotype, photogravure and other processes with the chromic salts,

because the luminous action through the bare glass, or nearly so, which in

the negative represent the shadows and half blacks, is more energetic in

proportion than through the other parts, from which it results that these

parts being most acted on are made deeply insoluble through the thickness

of the film, and then require to be cleared by a treatment with water at a

higher temperature than the parts representing the half tints in the

lights of the picture, which are but superficially and slightly insoluble,

can stand.



From time to time during the exposure the print in the photometer is

examined, and when a certain picture is printed to a certain shade, or

when the one next by commences to appear or is faintly printed, etc., the

exposure of the tissue is sufficient.  This, as the reader has already

inferred, is a matter of experience, the guide being the knowledge of the

intensity negative tested as above explained.



_Development.--_The carbon prints are developed either on a sheet of paper

upon which it should remain (single or simple transfer), or on a provisory

support to be afterwards transferred on paper or any other material

(double transfer).



_Simple Transfer.--_This process is quite simple: The impressed tissue and

a sheet of paper coated with alumed (insoluble) gelatine are immersed face

to face in cold water, and when the tissue is softened both are removed,

one superposed on the other, and the whole, being placed on a glass plate

and covered with a thin oil cloth, is firmly pressed into contact with the

squeegee.  The rationale of applying under water the tissue on the

gelatinized paper is to avoid the interposition of air bubbles.



To operate by simple transfer the tissue should be impressed under a

reversed negative.  The reason is obvious.



_Double Transfer.--_By this method the carbon prints are generally

developed on porcelain or opal plates, which more easily than glass plates

permit one to follow the progress of the development and to retouch the

imperfections before transferring the picture on paper.



In order that the image does not adhere on the provisory support a little

of the following mixture is spread over the plate, which is then pretty

strongly heated, and, when it has cooled down, polished lightly with a

piece of white flannel to obtain a very thin and even layer free from

striae.  If the plate has not been used before for the purpose in question,

it should be waxed a second time in the same manner:



Yellow wax              4 parts

Rosin                   1 part

Turpentine or benzine   250 parts



The plates can be developed on the plates so waxed, but for "full gloss,"

that is, for enameled pictures, a film of collodion is applied on the

plates, which then, instead of being waxed, should to be simply flowed

with a solution of India rubber 1 to 100 of benzole:



Ether        250 parts

Alcohol      250 parts

Castor oil   1 part

Pyroxyline   5 to 6 parts



When the plate is coated and the collodion film set, it is immersed in

water until greasiness has disappeared and wanted for use.  Then the

tissue, previously soaked in water, is applied upon it (taking care to

avoid air bubbles) and squeezed, lightly at first, with some force

afterwards, to insure a perfect contact.



Zinc plates are also employed as provisory supports instead of glass, opal

or porcelain plates.   The modus operandi is exactly the same.(30) The

plates should be well planed, free from scratches, etc., and well polished

to obtain glossy pictures without one having recourse to a film of

collodion.  For matt pictures, i.e., without gloss whatever, the plate

should be finely granulated, and when waxing a very light pressure should

be exerted to remove the excess of wax, else it might be quite impossible

to strip off the picture in transferring on paper.



For double transfer on biscuits, objects in alabaster, porcelain, wood,

any even or curved rigid materials, flexible supports are employed to

develop the pictures.  These supports are prepared by fastening albumen

paper on a board and evenly brushing over the following hot compound,

filtered through flannel, which, when dry, is polished with a cloth:

Stearine   15 parts

Rosin      3 parts

Alcohol    100 parts



The flexible supports should be waxed, then collodionized for full gloss,

as the glass, porcelain and metallic plates.



Another method which the writer recommends is the following, due to Mr.

Swan: Immerse a sheet of paper in a solution of India rubber, 4:100 of

benzole, and let dry, which requires a few minutes.  This is the flexible

support.  Then after exposure, brush over the India rubber solution on the

carbon tissue, apply upon it the support when the benzole is evaporated,

and pass the whole under a rolling press to secure adhesion, then develop.

To transfer, soak the proof in tepid water, apply it on the material

prepared, as it will be explained further on, and when dry, imbue the

support from the back with benzole, to soften the India rubber, and strip.



To dispense with a rolling press, the proof may be developed on lacquered

vegetable paper prepared by immersion in a solution of 10 parts of red

shellac in 100 parts of alcohol.  After developing the proof is coated

with alumed gelatine, and when dry transferred as usual. To strip off it

suffices to imbue the paper with alcohol in order to dissolve the shellac.



When the picture must be transferred on small spaces or on small objects

the most simple method--the most effective, perhaps--is the following,

devised some years ago by the writer and now employed for the ornaments of

"articles de Paris:" Prepare the provisory support as usual, but with a

thicker film of collodion; then, after developing and coloring, if

necessary, the picture is coated with gelatine, to which may be added some

zinc white or other colored substance to form a ground.  This dry, strip

off, immerse the pellicle in water to soften the gelatine and transfer on

the material collodion side up.



The proofs should be developed within three or four hours after

insolation, for the luminons action continues pretty actively in the dark,

and this for a long time; thus: a proof rightly exposed in the morning

behaves as one over-exposed if developed in the evening, and after a

certain period either can not be developed or refuses to adhere on the

support.  However, the proofs can be kept for three weeks, may be more,

before development, if the soluble bichromate be washed off, the tissue

sponged and dried rapidly in the warm season.  This capital improvement is

due to Mr. Charles Brasseur.



It has been said that before being applied on the support the proof should

be immersed in water to soften the tissue.  The time which it should be

allowed to absorb water has an importance which must not be neglected.  If

it do not remain long enough to be soaked through, small invisible air

bubbles are formed on its surface, and interposing themselves between the

image and the support, form minute, brilliant, silver-like spots on the

finished picture; and, if the temperature of the water is above 20 deg. C.

(68 deg. Fahr.), the image will be more or less reticulated.  The

temperature depends a good deal of the softness of the gelatine; 15 deg.

C. (59 deg. Fahr.) is safe, except, however, when the thermometer is in

the thirtieths (90th Fahr.), when the water should be cooled down a few

degrees lower, but not at the melting ice temperature, for then the proof

would not adhere well.  As a rule, the tissue should remain in the cold

water until it becomes flat and shows a tendency to curl up.  It is at

this very moment that it should be squeezed on the support.



The proofs should not be developed immediately after transferring.  The

adherence is greater and the pictures finer and devoid of defects when the

development is made half an hour, and even an hour, after.  If developed

too soon the picture will be partly, and even entirely, washed off.

Hence, a number of transfers can be prepared beforehand, placing them,

face to face one upon another, in order that the tissue does not dry,

which is quite essential.



To develop, the plate, with the tissue adhering to it, is placed in water

heated to 30 deg. C. (80 deg. Fahr.), where it is left rocking the tray

occasionally until the paper rises up by itself at the corners, when

taking hold of it by one corner, it is stripped off, leaving behind the

image buried in soluble gelatine.  Should the paper offer any resistance

whatever, the gelatine should be allowed to become more soluble by

increasing the temperature of the water, or by a longer immersion.  There

is, in fact, no objection to this.  The plate--and that is a good

method--can be placed in an upright position in a tin box, made ad hoc, and

left therein in warm water until the paper detaches itself and the image

is partly developed _and the bichromate washed off._  This done, the plate

is held in an inclined position on a tray filled with water at 35 deg. C.

(95 deg. Fahr.), which is dashed with a wooden spoon on the image to clear

it from the non-acted-on gelatine.  Presently one can judge whether the

exposure is right.  If it is too short, the half tints in the shadows are

washed off, unless the negative be too intense, when a similar effect also

occurs in the whites.  If it is too long, either the image is with

difficulty cleared or remains undeveloped.  In the latter case, it is

recommended by some operators to increase the temperature of the

developing water to near the boiling point, and, for local clearing, to

pour it on.  This we find objectionable, for the half tints are easily

washed off.  A better process, when the picture can not be cleared by

water at 50 deg. (122 deg. Fahr.), or thereabout, is to use a solution of

common salt at 5 or 6 per cent. of slightly warm water.(31) It is even

preferable to finish the development in a tepid solution of potassium

sulpho-cyanide, 12:100.  The dissolving action is long, but not only, as

said above, the half tints are best preserved, but blistering  and local

washing-off are avoided.



After development the plate is rinsed under the tap, then flowed two or

three times with a solution of chrome alum at 1 per cent. of water, then

washed, and finally allowed to dry spontaneously.



It is objectionable to use a strong solution of alum, and in it to immerse

the plate for any length of time; the gelatine is considerably

hardened--which is not necessary--and more liable to crack by time in being

thoroughly desiccated.  We discard the common alum which we found liable

to produce a slight reticulation.



Two defects are complained of by the beginners, viz., the want of

adherence of the deep blacks, and, especially, the isolated and fine lines

when the picture is a reproduction of an engraving, a drawing, etc., and

the liability in half tone pictures of the delicate details being washed

out.  The first defects are avoided by pouring a solution of boric acid on

the transitory support before applying the tissue and developing at a low

temperature with salted water.  The second from an imperfect knowledge of

the properties of gelatine acted on by light in presence of a salt of

chromic acid.  One should bear in mind that the degree of solubility of

gelatine so acted on, as also its degree of impermeability--which is

important in certain processes of photogravure--is proportionate to the

degree of insolation; thus, when not impressed, bichromated gelatine

dissolves in water heated to about from 25 to 30 deg. C. (77 to 80 deg.

Fahr.), and when acted on between 30 and 100 deg. C. (86 to 112 deg.

Fahr.), according as to the degree of insolation, that is, of reduction of

the chromic salt, the latter temperature being that of insolubility of the

parts the most acted on.  The very delicate half tints do not, generally,

stand a temperature higher than 35 deg. C. (95 deg. Fahr.), and,

therefore, as the degree of insolubility of the various parts cannot be

ascertained, a priori, it is advisable during the development to increase

gradually the temperature of the water from this degree, and not to exceed

45 deg. C. (113 deg. Fahr.), in order to obtain the most perfect result

from a negative of good intensity.  Indeed, by placing the supports on a

rack and immersing the whole in water heated to 30 to 35 deg. C. (86 to 95

deg. Fahr.), the image will clear up by itself to perfection in a certain

period.  This method is excellent for proofs in lines.  Those from the

grained negatives employed in photogravure are still more perfectly

developed in a tepid solution of potassium sulphocyanate, since the

impressions wholly consist of insoluble parts (the lines) and gelatine not

acted on.



_Retouching.--_The retouches are easily made. They should be done before

transferring when working by the double transfer process.



The transparent spots, and any parts which should be altered, are

retouched with the material of the tissue dissolved in warm water; the

whites are cleared with a scraper; and any parts which are not intense

enough, or which should be blended by the addition of half tints, are

worked on the proof--to which a tooth has been given by rubbing with

cuttle-fish powder--by means of a stump and an appropriate color, a mixture

of lamp-black and carmine, for example, in very fine powder.



The proofs can also be colored by chemical means (see further on), or with

water colors employed with a solution of chrome alum, 1 to 200 of water,

or gilt, silvered or bronzed with metallic powders applied with the

gilder's size thinned with turpentine on the proof previously coated with

a thin layer of alumed gelatine.



_Second Transfer.--_To transfer, a sheet of enameled or simple transfer

paper is immersed in tepid water until the gelatine is softened and feels

slippery to the fingers.  The support is then placed under water at

ordinary temperatures--not under 16 deg. C. (60 deg. F.)--for two three

minutes, then rubbed with a camel brush to remove the air bubbles, which

might be formed on the surface of the image, when, without draining, the

gelatinized paper is laid upon it, covered with the thin oil cloth, and

pressed into contact with the squeegee, commencing in the center to the

sweep off the water, then repeating the operation for the other half, as

explained to apply the tissue on the provisory support.  When the whole is

quite dry, which requires three or four hours, the edges are cut with a

penknife and the whole stripped off.  It may happen that the proof is

covered with minute, silver-like brilliant spots, which are nothing else

than very small air bubbles interposited between the carbon proof and the

transfer paper. They are caused by the gelatine paper not having been

sufficiently softened or not laid on the proof with proper care. The

defect may also arise from the transfer paper coated with not sufficiently

thick gelatine.



To transfer on any rigid material, the proofs on flexible supports are

coated by floating on the following gelatine solution, then allowed to

dry, and, when wanted for use, immersed in tepid water to soften the

gelatine and secure adherence:



Gelatine                   50 parts

Water                      400 parts

Solution of chrome alum,   6 parts

4:100



_Development on Absorbing Materials.--_The development of carbon prints on

absorbent material--such as canvas and palettes to be painted in oil,

etc.--cannot be made in the ordinary manner on account of the impossibility

to eliminate entirely the chromic salt which tinges the material yellow.

To turn the difficulty, it suffices to wash off in several changes of cold

water all the unaltered bichromate from the prints on their removal from

the printing frame, and to proceed as usual, or the prints can be allowed

to dry and transferred at some future time.



Canvas should be prepared by brushing with a solution of aqueous ammonia

in alcohol, 5:20, to remove greasiness until the thread is apparent, and,

when dry, rubbed with sand to grain it--or to give a tooth, as it is

termed--then rubbed dry with a solution of soluble glass, 1 to 10 of

beer.(32)



Palettes should be rendered impervious, or nearly so, by flowing upon them

a solution of alumed gelatine, which is allowed to penetrate into the

pores of the wood and the excess scraped off when solidified, when the

surface may be whitened, if necessary, as for printing on wood box, q.v.



Opals, porcelain, or ivory should be prepared with the following

substratum:



Gelatine             50 parts

Water                400 parts

Chrome alum, 4:100   6 parts



Very fine carbon proofs having the appearance of pictures on opal plates

are made by transferring in the following manner, devised by the author:



Develop on the ground surface of a glass or porcelain plate, well waxed,

to obtain a matt picture, or in the ordinary manner for "full gloss," and

when the image is retouched or colored, apply a thin coating of gelatine,

let dry and coat with the following opaque collodion:



A.   Ether, conc.         100 parts

     Alcohol, 95 deg      90 parts

     Pyroxyline           7 parts

B.   White zinc in very   9 parts

     fine powder

     Castor oil           3 parts

     Alcohol              10 parts



Grind in a mortar, adding ultramarine blue and carmine, or a little of any

suitable coloring matters, and mix to A. When the collodion is dry, which

requires a few hours, strip the whole or back with strong white or colored

paper before stripping. A solution of gelatine with glycerine, white zinc,

etc., may be substituted for collodion when the pictures are employed as

ornaments on wood, etc. Carbon prints on celluloid are now made for

similar purposes.

OPAL GELATINE SOLUTION

Gelatine      150 parts

Glycerine     15 parts

Zinc, white   40 parts

Water         600 parts



To which some coloring matters may be added according to taste.  Grind the

white with the glycerine and a little water, mix to the gelatine dissolved

in the remainder of water, and filter through canvas.  Apply the mixture

moderately hot, 30 deg. C. (86 deg. Fahr.)



_Transparencies.--_The transparencies are printed on a special tissue sold

under the name of "diapositive."  It differs from the ordinary tissue in

this, that the mixture contains a greater quantity of the color matter,

India ink, which is ground exceedingly fine.



The proofs for transparencies should be printed deeper than those to be

seen by reflection, and developed on thin glass plates, free from any

defects, and coated with either one of the following substrata:



Soluble glass   5 parts

White of eggs   15 parts

Water           20 parts



The whole is beaten up to a thick froth and allowed to subside, when the

clear liquid is decanted, filtered through flannel and the glass plates

coated.  The substratum should be allowed to dry for a few hours, and

rinsed under the tap before use.



The other substratum consists of



Gelatine             35 parts

Acetic acid, No. 8   250 parts

Alcohol, 95 deg      50 parts

Water                700 parts

Chrome alum, 4:100   60 parts



Dissolve the gelatine in the acid at a moderate heat, add afterwards the

alcohol and water, and lastly mix the chrome alum by small quantities at a

time.



These substrata are employed to avoid the peeling off of the image.  To

prevent the entire desiccation of the gelatine, which is the cause of the

defect above alluded to, it is advisable to add glycerine to the washing

water after the image is cleared.  Some operators recommend a coating of

flexible collodion, that is, prepared with castor oil, for the purpose in

question.  We do not think that necessary when the transparencies are not

exposed to sunshine.  If anything should be applied we would prefer the

encaustic.



Carbon transparencies are invaluable for reproducing negatives in the

original size by the same (carbon) process, or for enlarging by the

collodion or gelatine process.  For these purposes they should be made on

the special red tissue manufactured by the Autotype Company, of London,

Eng.  They can, however, be made on the ordinary tissues.



Whatever be the tissue employed, the transparencies for the reproduction

of negatives are seldom opaque enough, and should be intensified.  This is

done by treating them with a very dilute solution of sodium permanganate,

which colors them olive green.



Transparencies for lantern slides, etc., are best colored with the

couleurs a l'albumine of L. Encausse, sold by J. Reygondaud, Paris

(France).  They are transparent.(33)



_Toning and Intensifying.--_The carbon proofs can be toned and at the same

time intensified by reagents acting with chromic oxide.



The dyes or coloring matters precipitated are not opaque, and, as a

consequence, not objectionable for transparencies.  The following

processes are the most employed:



Prepare three solutions as follows:



A.   Ferric sulphate    5 parts

     Water              100 parts

B.   Sodium carbonate   2 parts

     Water              100 parts

C.   Gallic acid        5 parts

     Water              100 parts



Dissolve the gallic acid in warm water.  Filter each solution.  They keep

well.



To tone, the plate is immersed for, say, ten minutes in A, then, after

rinsing slightly, it is placed in B for the same period, rinsed again and

flowed with C until the desired color is obtained.  The tone is a splendid

purple black color.  If a solution of pyrogallol be substituted to that of

gallic acid, the tone is green, and to a green bordering to black when a

solution of catechu is used, the catechu exerting at the same time a

tanning action on the gelatine.  After toning, the plate should be

thoroughly washed.



A similar process consists to wet the plate under the tap, then to flow

over a mixture by about equal volumes of



A.   Ferrous sulphate     5 parts

     Acetic acid, No. 8   5 parts

     Water                100 parts, filter

B.   Gallic acid          5 parts

     Water                100 parts



When toned, the plate is well washed, then flowed once with the alum

solution and again washed.  The tone by this process easily turns to an

inky blue not very agreeable.  The action should be stopped a little

before the desired color is obtained.



It sometimes happens that the image in drying intensifies more then

necessary.  It can be cleared with a solution of oxalic or citric acid.



A brown sepia is obtained by toning first with potassium permanganate, 1

per cent. of water, then, after washing, with a solution of pyrogallol.

If gallic acid be used instead of pyrogallol, the tone is black.  By this

process a great intensity is obtained.  A dilute solution of ammonium

sulphide can be employed as a clearing agent.



Pyrogallol and silver nitrate give a warm black tone.



Potassium bichromate followed by silver nitrate form a brick-red

precipitate of some opacity.(34)



Chloride of nickel and potassium ferrocyanate produce a fine brown.



Lime water and alizarine dissolved in alcohol dye violet.



Alizarine and the caustic alkalies produce a variety of tints, from violet

to purple, according to the concentration of the solutions.



Lead acetate and alizarine in ammoniacal solution dye purple.



Potassium ferrocyanide and uranium nitrate produce a warm sepia tone. With

chloride of nickel the tone is brown.



Ammoniacal solution of coralline diluted with water gives carmine red.



Potassium bichromate and extract of indigo produce a fine greenish tone

suitable for landscapes.



Extract of indigo colors blue(35)



Some of these reactions can be applied to the printing processes with the

bichromates, etc.  The paper should be coated with galatine.  See the

Appendix.



Other colorations can be obtained with dyes in utilizing (as shown by

Persoz) chromous chromic oxide as a mordant: alizarine, Brazil and yellow

wood (morus tinctoria), Fustet (rhus cotinus), etc.  The extent of this

work does not admit of describing the numerous processes which can be

employed; they will suggest themselves to the chemist.



The alkalies employed with the dyes should be employed in diluted

solutions, as being liable to produce reticulation.  By applying the

coloring matters and the mordants thickened with a little starch, the

image can be colored with different colors.  Lantern slides can be thus

colored with great ease.







PREPARATION OF RED, YELLOW, OR BLUE TISSUES.





_Red Tissue.--_Dissolve 10 grams of carmine in 1 liter of aqueous ammonia

and evaporate.  When the smell of the alkali has almost disappeared, add 1

liter of rain water.  Of this take 65 cubic centimeters, add 35 c.c.m. of

rain water, and in the solution let soak for an hour 15 grams of very

soluble gelatine, add 1 gram of sugar, and dissolve in a water bath.

Filter, and take of the mixture a sufficient quantity (25 c.c.m. for a

surface 18x24 centimeters) to cover a sheet of paper which has been

previously applied upon a glass plate in the following manner: In a tray

full of hot water, immerse the plate and the paper; remove the whole in

such a manner as the paper remains in contact with the plate; rub out the

excess of water with a squeegee, and flow the gelatine over the paper

still damp.  Let cool on a leveled stand, and when the gelatine is

solidified to a consistent jelly, remove the paper from the plate and

place it to dry in an oven heated at not over 24 or 25 deg. C.



It is desirable that in drying the paper does not curl up.  To that end,

apply over it, before it being removed from the plate a wooden frame to

which the gelatine, still sticky, will sufficiently adhere to hold the

tissue when it stretches in drying.



_Yellow Tissue.--_Pulverize to an impalpable powder 25 grams of light

chrome yellow in tablets (water color), and gradually add in stirring 1

liter of rain water.  Take 100 c.c.m. of this and into it let soak for an

hour 15 grams of the same gelatine used for the red tissue, add 1 gram of

sugar, then proceed as above.



_Blue Tissue.--_In a liquid consisting of 85 c.c.m. of rain water and from

12 to 15 c.c.m. of blue ink, such as sold by stationers, let soak for an

hour 15 grams of the same gelatine and 1 gram of sugar, and proceed.



_Preparation of Transfer Paper.--_Two kinds of transfer paper are

employed--the enamel and plain transfer paper.



To enamel the paper: Dissolve 100 parts of barium nitrate in 500 parts of

water, and, on the other hand, 200 parts of sodium sulphate in the same

quantity of water.  Mix, wash well the precipitate--barium sulphate--by

decantation, and when well drained, mix to the following solution:



Gelatine, Coignet's   300  parts

Glycerine             80  parts

Ultramarine blue      1  part

Crimson lake          0.1 part

Water                 2,500  parts



Let soak the gelatine for, say, one hour, dissolve by heat, then add by

small quantities, stirring violently, 4 parts of chrome alum dissolved in

250 parts of hot water.  Filter through flannel and coat the paper as

directed to prepare the tissue.  The mixture should be employed

immediately after adding the chrome alum.



The plain transfer paper is prepared in the same manner, leaving out the

barium sulphate and the coloring matters.



_Preparation of the Silver Paper.--_Immerse the paper for two minutes in a

solution of--



Sodium chloride (common   2 parts

salt, dry)

Lemon juice               1 part

Water                     100 parts (filter)



When dry and wanted for use, sensitize the salted paper by floating for

one minute on--



Silver nitrate   8  parts

Nitric acid      0.1 part

Water            100  parts



On its removal from the silver bath, sponge the paper between sheets of

blotting paper and hang it up to dry.



ENCAUSTIC FOR SINGLE TRANSFER PROOFS.

White wax           25 parts

Mastic              3 parts

Turpentine          100 parts



Dissolve by heat, first the mastic, then the wax, and keep for use in a

large mouthed vial.



      MATT VARNISH.

Sandarac        6 parts

Mastic          6 parts

Lavender oil.   0.5 parts

Ether           100 parts



When dissolved, add 30 parts of benzine.  The opacity of the film varies

with the quantity of benzine added; by excess the varnish dries

transparent.



         WATER COLORS WHICH RESIST THE ACTION OF LIGHT.

Red.      Indian red.    Light red.

Orange.   Mars yellow.

Blue.     Cobalt blue.   French blue.   Smalt.         New blue.

Brown.    Raw umber.     Burnt

                         sienna.

Green     Terre verte.

Yellow.   Cadmium        Yellow         Roman ochre.

          yellow.        ochre.









APPENDIX.





Although we intended to only describe the printing processes without the

use of silver salts, we thought it would be well to complete this work by

giving the most practical and interesting processes ever published to

obtain permanent photographs; as they may give rise in the hand of

experimenters to useful applications.



From time to time processes are published under "queer" names, which are

based on the well known actions of reagents on the ferric salts reduced by

light.  They are derived from those described in the following pages.



We call specially the attention of the reader to the process of Poitevin,

by which one can experiment with every ferric salts, citrate, lactate,

oxalate, tartrate, benzoate, etc., by simply exciting with the

corresponding acid.  Observe that to obtain good results the paper should

be strongly sized; it is a sine qua non, although not recommended by

Poitevin.







C.J. BURNETT'S PROCESS(1857).





"A capital process for many purposes," says Mr. Burnett, "is to float or

_steep_ the paper in a mixed solution of bichromate of potash and sulphate

of copper, as for Hunt's chromotype process.(36) I have mixed gelatine, or

occasionally grape sugar, or both with the solution;(37) but instead of

developing it with nitrate of silver, as in chromotype, wash out the salt

unaltered by light, and develop by floating on a solution of ferrocyanate

of potassium.  The purple red color of the copper salt which now forms the

picture may be modified or changed in many ways,(38) viz., by soaking the

picture, after the ferrocyanate of potassium has been washed out of the

lights, in a solution of sulphate of iron.  Solutions of gallic acid,

tannic acid with alkalies of carbonate, may also be employed to modify or

change the color.  This process has the advantage that one may regulate

the exact tone (black or useful neutral tint) to the greatest nicety by

the time we allow the print to remain in the iron toning bath."







GODEFROY'S PROCESS (1858).





Float the paper upon the following solution for three minutes and hang it

up to dry:



Uranium nitrate   30 to 60 parts

Silver nitrate    8 parts

Water             100 parts



(39)



The sensitiveness increases in proportion to the quantity of uranium

nitrate.  With the above formula the paper can be exposed in the camera,

or, for printing, under a negative cliche.



In printing an exposure of five seconds in diffused light gives an image

perfectly visible, and a grayish black tone; ten seconds gives a vigorous

image almost of a black color; in from fifteen to twenty seconds the image

is very strong, with the color of an engraving. In sunshine the action is

necessarily much more rapid.



The impression is developed by immersion in



Ferrous sulphate   8 parts

Tartaric acid      4 parts

Sulphuric acid     1 part

Water              100 parts



The image is rapidly developed. It is fixed by washing in water.







DE LA BLANCHERE'S PROCESS (1858).





Uranium nitrate   25 parts

Distilled water   100 parts



Filter the solution and keep it in the dark.



The paper should be sized with a gelatine solution at 5 per 100 of water,

and, when dry, kept in the dark.(40) It is sensitized by floating five

minutes.



The exposure under a negative varies from fifteen to twenty minutes in the

shade, and from one to three minutes, at the most, in sunshine.  As a

rule, it is advisable to somewhat underexpose in order that the

development be regular, progressive, under control.



The image is developed by floating, or immersion in



Silver nitrate       2 parts

Distilled water      100 parts

Nitrate acid, C.P.   a trace



When the image is intense enough it is washed in several changes of water,

then toned in a solution of gold at 1 per 1,000 of water acidified with

traces of hydrochloride acid.(41)



The following bath develops slowly, and gives very rich purple tones

without toning:



Nitrate of silver    3 parts

Nitrate of uranium   1 part

Nitrate of cadmium   1 part

Alcohol              10 parts

Water                100 parts

Nitric acid          traces



_The developing solutions should be as little acid as possible, but not

neutral, for then the proofs would be veiled and grayish._



The image can also be developed in a solution of gold, or in a very weak

solution of mercuric chloride at 1 per 10,000.  The proof must be

extremely well printed and left for from two to five minutes in the

mercuric solution.  If the time of exposure is right, the image will

change but little in the solution, and will take, when treated with silver

nitrate, the most splendid tones.



The proofs should be carefully washed when finished.  If they were

developed with silver, they must be immersed in diluted aqueous ammonia,

which will perfectly clear the whites.  If developed with chloride of

gold, the water should be heated to 60 to 80 deg. C. (140 to 176 deg.

Fahr.)







HOUDOY'S PROCESS (1858.)





The paper is floated upon a lukewarm solution of gelatine at 5:100, and

when dry, on a bath of uranium at 10 or 15 per 100 of water.  After

exposure to the sun the image is developed with a solution of silver

nitrate acidified with acetic acid.  The exposure varies, according to the

nature of the negative, from one to ten minutes; it must be long enough

for the image being developed in from thirty to forty seconds.  It is then

removed from the silver bath and placed in the following:



Ferrous sulphate   3 to 8 parts

Acetic acid        2 parts

Water              100 parts



In this bath the image takes a great vigor and appears entirely on the

surface of the paper.  When the proof has been too long exposed it should

be washed slightly before placing it in the iron bath.  Developed, the

image is, generally, of a sepia tone, which can be turned to black by a

solution of chloride of gold, 1:1,000, washing afterwards as usual.







NIEPCE DE ST. VICTOR'S PROCESS (1859).





Red Prints.





Float the paper for fifteen or twenty seconds on a 20 per cent. solution

of nitrate of uranium and dry before the fire in the dark room.  This

paper can be prepared many days before use.  Expose in sunshine from eight

to ten minutes, according to the intensity of the light and the quality of

the negative, then wash in moderately warm water (50 to 60 deg. C.) for a

few seconds.  This done, immerse in a solution of red prussiate of potash

at 2 per cent. of water; in a few moments the proof will become of a fine

blood-red color, like "sanguine."  Wash, etc.





Green Prints.





Make a red print as above described, immerse it for a few minutes in a

solution of nitrate of cobalt and dry it without washing.  Fix then in a

solution of sulphate of iron at 20 per cent. of water and 4 of sulphuric

acid.  Wash and dry before the fire.





Violet Prints.





Prepare the paper in the uranium bath, expose, wash and develop in a

solution of chloride of gold, 1:200, until the proof has assumed a fine

violet color.  Wash in several changes of water.





Blue Prints.





Sensitize the paper with a red prussiate of potash solution at 20 per 100.

Let dry, expose until the proof is slightly blue; immerse it for five or

ten seconds in a saturated solution of bichloride of mercury, wash only

once and immerse in a solution of oxalic acid--saturated when cold--heated

to about 55 deg. C.  Wash in three or four waters and let dry

spontaneously.





Black Prints.





Float the paper on a mixture by equal volumes of a solution of iron

perchloride and another of uranium nitrate, each at 10 per 100 of water.

Expose and develop on a saturated solution of gallic acid.







                    DR. T.L. PHIPSON'S PROCESS (1861).





Take a solution of perchloride of iron and, having precipitated the

peroxide with ammonia, collect the precipitate on a filter and wash it

with boiling water.  Add the precipitate in excess to a warm solution of

oxalic acid.  A beautiful emerald green solution is obtained, which must

be a little concentrated by evaporation and then set aside in a dark room

for use.  The paper is floated for ten (?) minutes upon the green solution

of ferric oxalate, to which has been added a little oxalate of ammonia and

hung up to dry in the dark.



Expose under a negative for from ten to twenty minutes, according to the

weather, and wash well the paper with rain water.  Spring water will not

do on account of the lime it may contain, which will form oxalate of lime

in the paper (insoluble).  When all the non-decomposed oxalate is washed

from the proof, a feeble image of oxalate of protoxide of iron, scarcely

visible, is left on the paper.  To develop it and to obtain the vigor, the

tone and color of silver prints proceed as follows:



Plunge the proof for a little while in a (weak) solution of permanganate

of potassium to which a few drops of ammonia have been added; in the bath

the image becomes brown and distinctly visible.  It is then withdrawn and

immersed in a solution of pyrogallic acid for half an hour, after which it

is washed and dried.



The image thus obtained can hardly be distinguished from silver prints;

the tone is soft, brilliant and permanent.



This process is quite original and interesting.  The theory is as follows:

Under the action of light the ferric oxalate is reduced in the ferrous

salt, insoluble, which, after the print has been cleared from the ferric

oxalate, is oxidized and reduced into ferric oxide by the alkalized

permanganate, the latter then forming colored compounds with reagents.



It has been lately published in England under the name of "kallitype," a

new process--or old, ad libitum--which consists in developing the image in

ferrous oxalate by a peculiar silver compound whose formula is given

below.  The paper is prepared by brushing with a strong solution of

neutral ferric oxalate dried rapidly--which is a sine qua non when using

deliquescent salts; and after exposure the image is developed, etc.



Silver nitrate         50 grains

Sodium citrate         800 grains

Potassium bichromate   1 to 2 grains

Water                  10 ounces



"Dissolve the silver nitrate in 1 ounce of water, the citrate and

bichromate in the remainder and mix.  The precipitate--silver citrate and

chromate--is then dissolved by adding 1 dram of ammonia .880, and after 35

drops of strong nitric acid has been added the solution is ready for use."



This process reminds us that of Robert Hunt (1842), and that of more

recent date (1863), of Borlinetto, who developed the image in black with a

silver nitrate alcoholic solution, 1:500, and after washing the picture in

a solution of citric acid, 1:10, fixed it by aqueous ammonia.  But,

although that is not absolutely necessary, we would advise one working

this, or similar processes in which a silver salt is employed for

developing, to fix the image, after treatment with citric acid to clear

the proofs from iron salts, in a solution of ammonium sulphocyanate--which

has not the injurious effect of sodium thiosulphate (hyposulphite)--in

order to prevent the paper to be tinged by the reduction of the silver

nitrate which is mechanically retained in its fiber.



The solution of ammonium sulphocyanate should be compounded with auric

chloride to tone the picture at the same time it is fixed; thus:



Ammonium sulphocyanate   35   parts

Gold terchloride         0.15 part

Water                    350   parts



The solution can be used over again.



In the processes devised by Dr. Phipson, Monckhoven and other authorities,

the double ammonio-ferric oxalate is rightly recommended instead of the

simple oxalate.  Not only is the preparation more sensitive to the

luminous action, but better half tones are obtained. As usual, it is

advantageous to size the paper with starch.



The ammonio-ferric oxalate is prepared by precipitating ferric chloride or

sulphate by aqueous ammonia, then washing the precipitate collected on a

filter until the washing water be neutral or does not evolve the smell of

ammonia.  The precipitate is then placed in an evaporating dish, and by

small quantity is added a hot solution of ammonium oxalate until it is

nearly (not entirely) dissolved, when the solution is set aside for a few

hours, then filtered and evaporated to crystallization.  For use, the

crystals of ammonio-ferric oxalate are dissolved in the proportion of 1

for 5 of distilled water.  The solution as well as the crystals should be

kept in the dark.



If one object to the trouble of crystallizing, the solution can be

prepared by dissolving the ferric oxide in a hot solution of 30 parts of

ammonium oxalate and 25 parts of oxalic acid in 180 parts of water

observing that the oxide must be in excess.(42)



The following sensitizing solution gives also excellent results:



Ammonio-ferric oxalate   10 parts

Ammonio-ferric lactate   4 parts

Water                    100 parts



After exposure, which varies from five to ten minutes, according to the

intensity of the light and the printing quality of the negatives, the

picture appears negative from formation of ferrous oxalate.  It may be

developed in a great many ways: by a solution of silver nitrate at 2 or 3

per cent. of water acidified slightly by an organic acid--citric acid, for

example--or a diluted solution of ammonio-nitrate of silver, which most

likely constitutes the best developer; the image is black and consists of

metallic silver and ferric oxide, with formation of silver oxalate, which

dissolve in the ammonia.  If the print be treated by a weak solution of

aqueous ammonia, the image turns green, then brown, and if, before the

latter coloration is obtained, gallic acid or pyrogallol be added, the

image becomes bluish-black or brown-black. In the same circumstances

tannin (gallo-tannin) produces a blue-black image; catechu-tannin(43) and

quino-tannin give green, etc. Employed as a developer, potassium

ferricyanate develops an image in prussian blue, and auric chloride one in

the characteristic violet metallic gold.  To fix the images obtained by

the latter reactions, it suffices to wash them in a few changes of water,

and, if developed with silver, they can be toned by any of the alkaline

solutions of auric chloride used in the printing out silver process, etc.



The photographs obtained by all these processes are permanent.







DR. J.B. OBERNETTER'S PROCESS (1863).





Copper chloride             100 parts

Ferric chloride, sol. sp.   13 parts

gr. 1.5

Hydrochloric acid, conc.    12 parts

C. P.

Water                       1,000 parts



Float the paper on this solution for about two minutes and hang it up to

dry.  The keeping quality of the prepared paper is remarkable; it has been

kept for two years without apparent change; its sensitiveness is at least

one-third greater than that of silver albumen paper.  Unless developed

within an hour or two, the vigor of the proof is much impaired; after

twenty-four hours a print can be taken over on the same.



When exposed, only a faint image is visible.  It should be fixed in the

following solution:



Potassium sulphocyanate   12 parts

Sulphuric acid, conc.     1 part

Sensitizing solution      10 to 12 parts

Water                     1,000 parts



A print is floated on this solution, face downward, for three or four

minutes, taking care to agitate the liquid as little as possible; the

print is afterwards immersed and another one floated in its place, thus

proceeding until all the prints are immersed or the solution can hold no

more.  A fresh solution is then added to strengthen it: the older the

solution the more rapidly and better it works.  In this developer copper

cyanide is precipitated on the parts acted on by light, and this exactly

in the proportion to the luminous action.  The time of immersion depends

on the method selected to finish the proofs; it its from five minutes to

half an hour.  If the proof is immersed for, say, twenty-four hours, the

image comes out in a relief which may bring the shadows to two lines in

depth.  When well developed and thoroughly washed, the proof can be dried

and the subsequent operations made at any convenient time.



Various processes may be employed to give to these proofs the tone

required; thus: the prints well washed are placed in a solution of

ferricyanate of potassium at 6 to 12 per 100 of water, where they take a

red color increasing in intensity.  If left over night the color becomes a

splendid velvet deep red with perfect clear whites.  To obtain the color

of silver photographs one hour's immersion is sufficient.  After this

operation the proofs are washed until the water is no more tinged yellow.



By immersion in

Ferrous sulphate      100 parts

Iron sesquichloride   40 parts

Hydrochloric acid     80 parts

Water                 200 to 300 parts



the proofs undergo the following gradation of colors: red, reddish violet,

blue-violet, black and greenish black.  As soon as the desired color is

obtained, the proofs are washed in acidified water and dried.



The most beautiful purple violet is obtained by leaving the proofs in the

iron solution until green-black, and then washing for a moment in a dilute

solution of sub-acetate of lead.



A brown-black may be produced by treatment, after washing, with an

ammoniacal solution of hypermanganate of potash.



A weak solution of nitrate of silver also yields very fine pictures, but

the exposure should be very short, and the proofs must be fixed in water

containing a small quantity of oxalate of ammonia.



In order to impart to the proofs the gloss of silver photographs, they

should be albumenized in the ordinary manner, and the albumen

insolubilized by well known means.



The chemical actions in this process I explain in the following manner: On

the paper there are Fe2Cl3 and CuCl, the latter in excess.  By the action

of light, and according to the transparency of the negative, Fe2Cl3 is

reduced to FeCl, while CuCl suffers no alteration.



If the paper be immediately placed in an _absolutely_ dry room after

exposure, the picture remains unchanged.  In a moist atmosphere FeCl

attracts moisture and, with a part of CuCl, is so decomposed that Fe2Cl3

is formed together with Cu2Cl.



After this action has commenced, if the proof be not immediately immersed

in a solution of sulphocyanate of potassium, Cu2Cl passes over to a higher

combination of chlorine, and the paper is again fit to be impressed anew

by the action of light.



As long as FeCl or even Cu2Cl is present, if the print is immersed in the

sulphocyanate solution, sulphocyanate of copper is immediately formed on

the reduced parts, while on the others the sulphocyanide of copper, formed

and dissolved by the sulphocyanide of potassium in excess, becomes decom-

posed with water in soluble sulphocyanide of copper and deposited as such

on the parts already covered with the salt.



Frequently the prints appear yellow from formation of the double

sulphocyanide of copper, but the color disappears by washing in water.

Red coloration is due to decomposition into ferrocyanide of copper.







L. LIESEGANG'S PROCESS (1865).





Pour ammonia into a nitrate of uranium solution, wash the precipitate of

uranate of ammonia in distilled water, then dissolve in citric acid.



Mix this solution of citrate of uranium and a little of a solution of

chloride of gold with a paste prepared by dissolving tapioca in hot water.

The quantity of chloride of gold must be small and the heat not too great,

otherwise the gold would be reduced.



Spread the mixture with a sponge on the paper, which takes a brilliant

yellow color, and expose when quite dry; the proofs have the delicacy and

vigor of albumen prints.



The proofs come from the frame with a bluish-black color; they should not

be toned, but merely fixed by washing until the yellow color of the paper

has disappeared.



The color of the picture can be changed to a purple by a solution of

chloride of tin.







GUARBASSI'S PROCESS (1867).





The paper is floated in the dark for four or five minutes on a saturated

solution of bichromate of potash.  When dry, it is printed a little longer

than for silver prints and afterwards floated, face upwards, on a water

bath until all the unaltered bichromate is dissolved.  It is then immersed

in the following solution, which improve by use and tones the pictures to

a reddish color:



Saturated solution       4 parts

nitrate of mercury, as

free from acid as

possible

Saturated solution       1 part

bichromate of potash

Distilled water          28 parts



This solution should be prepared, filtered and allowed to stand for some

time before use.  The print is left in the bath until it has assumed an

intense red color, the whites remaining perfectly pure.  It is then washed

and put in another bath to obtain a brownish tint.  This bath is thus

composed:



Conc. aqueous ammonia   2 parts

Distilled water         100 parts



The print must be immersed at once, and when, in a short time, it has

assumed the proper color, it should be washed immediately.



The picture is toned in a very diluted solution of chloride of gold,

1:7,000, in which the color passes from a light brown to a deep black or a

violet black tone, when it is washed in two changes of water.







A. POITEVIN'S PROCESS (1870).





"I use a paper prepared with iron sesquioxide rendered sensitive to light

by tartaric or, better, citric acid in concentrated solution.  This paper,

after desiccation and exposure to light, possesses the property of

reducing the solution of silver nitrate and that of chloride of gold, and

of turning blue with a solution of potassium ferncyanate in the parts

where light has reduced the iron sesquichloride into the oxide at the

minimum."



"To coat the paper with an equal layer of iron sesqnioxide, I brush it

with a tuft of fine linen dipped in a solution of iron perchloride at 10

or 12 per cent. of water, and dry the sheets in the dark.  I immerse

afterwards these sheets, one after the other, in a tray containing aqueous

ammonia, in such a manner as to well wet each sheet successively.  A

sufficient number of sheets being immersed, I pour off the ammonia in a

vial, and, in the tray, I wash them several times, and remove them one by

one to hang them up to dry, even in full light, the iron sesquioxide not

being sensitive to light."



"The paper can be prepared in quantities beforehand.  To use it I apply

upon each sheet a solution of citric acid at 30 or 35 per cent. of

water(44)--which may be done by daylight--and let them dry in the dark."



"Exposed under a negative of the ordinary intensity, the paper is

impressed in sunshine in a few minutes; in the shade it requires about the

same time as chloride of silver paper."



"After exposure the image is not visible, and without being obliged to

shelter it from light, I immerse the print in a solution containing about

1 per cent. of silver nitrate.  This solution can be used over and over

again, by adding to it a little of the silver salt.  It does not become

turpid by use; it simply turns slightly green from formation of iron

nitrate.  The image appears soon and rapidly becomes vigorous; in half an

hour it will be completely developed.  When the exposure is sufficient the

color is deep sepia, but not so intense if the quantity of citric acid is

feeble.  No fixing is necessary; it suffices to wash in several changes of

waters."



"The image can be toned with great facility by a weak solution of gold or

of platinum chloride, or, better, by a mixture of these two salts.  If the

impressed paper be treated by a very diluted solution of potassium

ferrocyanate, one obtains very pretty blue proofs."



"A weak solution of gold chloride develops a violet image. A solution of

platinum chloride has no effect."



"All the various phases of this printing method can be followed in full

(diffused) light; there is only the desiccation of the paper when

sensitized with citric acid, which requires to be done in the dark."













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