Peter C. Duchochois

HOW TO MAKE A NEGATIVE DRAWING

CHOICE OF PAPER. SIZING.

H. COOPER'S PROCESS (1865).

X'S PROCESS (1865). (Secrets of the Uranotype)

CAUSES OF FAILURES.

ARTIGUES' PROCESS

THE CARBON PROCESS.

APPENDIX.

Section 1.

Section 2.

Section 3.

Section 4.

Section 5.

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.

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Authors Quoted

Artigues.

Bevan, E.J.

Bingham

Borlinetto

Brasseur, Chs.

Buckle.

Burnett, C. J.

Chardon

Cheysson

Colas.

Cooper, H.

Cross, C. F.

De la BlanchÈre, 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

HÜbl, Baron.

Hunt, Robert

Liesegang, Dr. L.

Loeffler, J.

Monckhoven, Dr Von.

NiÈpce, 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.

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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 [pg 8] 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 [pg 9] 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 [pg 10] 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 [pg 9] 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 [pg 13] 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 “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 [pg 14] 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 [pg 15] 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 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 [pg 16] 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 [pg 17] 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 [pg 18] 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 [pg 21] 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.”