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The Silver Sunbeam:
A Practical and Theoretical Textbook
of Sun Drawing and Photographic Printing:
Comprehending All the Wet and Dry Processes at Present Known
with Collodion, Albumen, Gelatin, Wax, Resin, and Silver... Stereography.
by J. Towler, M.D.
New York, Joseph H. Ladd, Publisher, 1864.

"Dr. Towler was the editor of HUMPHREY'S JOURNAL OF PHOTOGRAPHY and other work s on photography.  The SILVER SUNBEAM was his best manual and the most often used of its day, going through nine editions. The contributors included:  Blanquart-Evard, John W. Draper, M. Carey Lea, R.J. Fowler, et al."



[pp. 164-170.]

HEREAFTER I shall devote a chapter to the stereograph and its philosophy; in this I shall simply give plain instructions for taking the stereoscopic negatives by the wet collodion process. For in-door work, and for out-door scenery where the objects are close at hand, a camera is required, which is furnished with two lenses of short focus, and of exactly equal power, for the production of stereoscopic negatives. These lenses are fixed in the same horizontal line; and about two inches and a half is the distance between their centers. Each lens can be attached to a separate slide, so that this distance can be slightly increased to two inches and three quarters, if found necessary. In the camera there is a vertical septum in the middle which divides it into two halves, one for each lens. This septum is nearly in contact with the collodion, and consequently makes a division line between the two images, which are taken on the same glass. The glasses for stereoscopic negatives are seven inches long by three and a half wide; I should prefer them eight inches by four, in order to have room for blunders and mishaps on the edges. The operation of focussing is the same here ‘as before, only that there are two lenses to be adjusted. Fix upon a certain object which is to be the central or most important one, and turn the camera so that it is seen in the center of one of the pictures of the ground glass. Where architectural objects occur in such pictures, the camera must be perfectly horizontal, if you intend the vertical lines to be vertical in the negative. If it happen that such architectural objects can not easily be comprehended in the negative, without tilting the camera, use this expedient; for, after all, the distortion which it produces on the print can be rectified in sonic measure afterward, by tilting the print in the stereoscope to the same amount. If portraits are to be the principal things, they must be placed in such a position artistically and photographically as to appear well, and at the same time in perfect focus; if certain objects are to be preeminent in esteem, direct your attention upon them when focussing, and regard the rest as secondary; and finally, if the whole landscape is the object, divide up the focus, or focus in such a manner that the view as a whole is tolerably sharp; this can easily be done by focussing an object at some distance, and by excluding all near objects from the print. In such cases, however, we require long-focussed lenses. For in-door operations the portrait combinations are used; for landscapes a pair of triplets, or of ordinary view lenses, produce excellent results. The globe lens of C. C. Harrison is all that can be desired for field work; it comprehends a larger angle than almost any other lens, and produces an irreproachable picture. Ross, Dallmeyer, and Grubb manufacture stereoscopic lenses for landscape photography, with which instantaneous pictures can be produced, and which in all other respects are highly commended by the intelligent amateurs of Great Britain. Jamin’s view-lenses produce very neat results, and are besides lower in price than those already alluded to.

In the ordinary stereoscopic negative, as in every negative, the pictures are laterally inverted, and when printed, this inversion is corrected only for each picture individually, for the right-side picture is still inverted and in the place of the left-side picture. In consequence of this, the printed stereo-graphs have to he cut apart, and mounted so that the right-hand photograph is placed on the right side, and the left-hand photograph on the left side. When taking pictures of still life, as also others, where the living objects are not in motion, it is very easy to manage matters so as to invert the photographs on the negative. The method is as follows:

Take a large-sized camera-stand, allowing sufficient space for the camera to slide laterally. Placing the camera in the right-hand corner, focus the left-hand lens. Next slide the camera gently, or lift it up and place it in the left corner, and focus the right-hand lens. The space between the centers of the two pictures thus focussed must be about two inches and three quarters. Whilst the camera is in this position on the left side, insert the sensitized plate, take out the slide, uncover the right-side cap for a second or two, and take this picture. Then close up the lens, lift up the camera gently and place it on the right side. In this position uncover the left-side lens for the same length of time. In this way, and in the space of ten seconds or so, the two pictures can be taken in a proper condition for printing so as to produce a non-inverted stereograph. For such work it would be no difficult task to contrive a slide by which a single lens would be all-sufficient; that is, when the camera is on the left side, the lens must slide to the right side, and vice versa on the right side.

As soon as the negative is thus taken, it has to be developed before it gets dry. The development and fixing can be performed in a dark tent specially arranged. for such purposes. Various contrivances have been adopted in landscape photography for these operations. For my own part I consider a simple hand-cart, with iron rods from corner to corner diagonally, in the form of send-ellipses, and covered with a balloon-shaped tent, a very practical accommodation. But each successful photographer is somewhat of a genius, and can easily arrange a dark chamber according to his own taste and materials on hand.

Negatives thus taken and fixed are placed carefully away in slides where they can not be injured during transportation home. In the evening, or the next day, or at any convenient time, the negatives are examined; if clear, transparent in the lights, and sufficiently intense in the shades, they are varnished. On the contrary, if the opacity of the shadows is not deep enough, although the appropriate gradation exists between the lights and shades, it will then be deemed necessary to proceed to intensification. Previously the edges of the negatives must be varnished to the depth of one tenth of an inch upon the collodion, to prevent its peeling off during the operation. This is effected by dipping the quill end of a feather into the varnish, and then running alone the edge of the collodion and of the glass, with this portion of the feather slightly inclined, so that the varnish does not drop oW a sufficient quantity is attracted upon the collodion as you proceed. After this put the negatives aside, that the varnish may become thoroughly dry and hard. As soon as it is dry, immerse the plates in rain-water, and allow them to remain there for about a quarter of an hour, by which time the collodion film will have become saturated with this fluid. Now you may commence the intensifying process, as before described in the chapter on collodion negatives.

Instantaneous Stereographs

There is no branch of photography that has so intensely attracted the attention of wealthy and intelligent amateurs as that of stereography; on this account we owe to them most of the discoveries in the art and the new incitement that has arisen in this department, that of Instantaneous Actinsim, has communicated a new impulse from which we derive fresh deductions and new results. The co-laborers in stereographic pursuits in Europe, but more especially in Great Britain, beginning with royalty downward to the rural gentry, are very numerous, very intelligent, and, best of all, very communicative. They take out no patents for their discoveries, they make no commerce with secrets, odious things which noble minds eschew. It is to such a goodly host of fellow-soldiers in the stereographic camp that we must attribute the riches of our knowledge. That light can act actinically the twinkling of an eye is no tax upon cultivated conceptions; for in this same wink, which to us is instantaneous, Light has run round the earth several times; in this twinkling, Light has seen more than man in his age can ever see; in this twinkling, millions of fresh portions of light have impinged on the model, and have rebounded to the lens and through it, and have nestled upon the sensitized film—we are justified then in expecting that instantaneity in photography is feasible. The sole questions present themselves:

What film is sensitive enough to receive it? What developer refined enough to produce the reduction? The questions are answered by facts. Instantaneous stereographs exist in great number, and the artists that produced them have bequeathed to the public their modes operandi. I can not do better than quote a few instantaneous processes. All amateurs agree in certain particulars, which conduce to success. The light must be very bright; the atmosphere very clear; the glass very clean; the collodion very ripe; the developer very sensitive, and the lens very well corrected, and capable of producing a sharp picture with a large diaphragm; the shorter the focus the better within proper bounds.

[Under construction - formatting incomplete - may contain OCR errors.]

Instantaneous Process of Lieutenant- Colonel Stuart Wortley.
Ether 1 ounce.
Alcohol, spec. gray., .802, . . 2 1/4 ounces.
Iodide of lithium, 15 grains.
Bromide of lithium, 6 1/2 grains.

The pyroxyline is first steeped in the iodo-bromized alcohol, and the ether then added.

Silver Bath.

Re-crystallized nitrate of silver, 35 grains.
Distilled water 1 ounce.

Iodized by leaving a couple of coated plates in the bath for several hours ; acidified at the rate of from two to three drops of nitric acid to the ounce of bath. Leave the plate in the bath longer than you would if the collodion contained only iodine.


Sulphate of iron 2 ounces.
Distilled water 12 ounces.

Acetate of lead 24 grains.
Water 2 1/2 ounces.

Mix the above solutions, and when the precipitate has all settled, decant off very carefully, and then add:

Formic acid, (pure,) 2 1/2 ounces.
Acetic ether, 6 drachms.
Nitric ether, 6 drachms.

From this stock-developing solution take as much as is required, and add acetic acid, according to the temperature, generally iii about the same quantity as the formic acid. The developer is kept on the plate until the necessary detail is brought out; after which the plate is well washed and fixed with a weak solution of cyanide of potassium.


Pour on a saturated solution of bichloride of mercury; as soon as the proper color is attained, flue plate is thoroughly washed, and a five-grain solution of iodide of ammonium in water is poured on and off until the desired depth has been attained. (The reader will comprehend the rationale of this proceeding by carefully perusing my remarks on this subject in a preceding chapter.) After this the following solutions are used:

No. 1.
Pyrogallic acid 12 grains.
Water 1 ounce.

No. 2.
Citric acid 50 grains.
Nitrate of silver 10 grains.
Water 1 ounce.

Pour a few drops of No. 2 into No. 1, and pour on and off until the negative has assumed the required density. After which wash the plate thoroughly in several waters, dry and varnish.

Valentine Blanchard prefers a bromo-iodized collodion, although under certain conditions he admits that a simply iodized collodion is more rapid, but at the same time there is less contrast. The silver bath is composed of re-crystallized nitrate of silver, forty grains to the ounce of distilled water, and saturated with iodide and bromide of silver. It is always supposed to be acid, to which is added a small quantity of moist oxide of silver; after the solution has beers sufficiently agitated, it is filtered, and then acidified by a weak solution of nitric acid, containing three or four drops of acid to one hundred of water. This acid solution is added very cautiously, until the picture is quite clear and free from fogging. A bath so prepared is very sensitive whilst new, and it is only whilst new that any bath is likely to produce instantaneous results.

The developer consists of the sulphate of the protoxide of iron, generally thirty, and frequently fifty grains to the ounce of distilled water, acidulated with glacial acetic acid, because the ordinary acid contains impurities.

The negatives, when they require it, are intensified with a saturated solution of bichloride of mercury in cold water, until the film is of a uniform gray color; they are then washed and treated with a solution of iodide of potassium, (one grain to the ounce of water,) by pouring it on and off until the film assumes a greenish-slate color. There should be no greenish line on the wrong side of the plate, for this is an indication that the strengthening has been carried too far.

Hockins uses simply iodized collodion; his bath contains thirty grains of nitrate of silver to the ounce of distilled water, and is iodized by throwing in a proper quantity of iodized collodion; it is then filtered. Two minims of pure nitric acid are added to each eight ounces of the bath, which is prepared twenty-four hours before using.

The developer consists of

Formic acid, (strong,) . . . 2 drachms.
Pyrogallic acid 20 grains.
Distilled water, 9 1/4 ounces.
Alcohol 1/2 ounce.

This is kept on the plate until the operation is complete.

Claudet’s Developer.

Pryrogallic acid 20 grams.
Distilled water 7 1/2 ounces.
Formic acid 1 ounce.
Alcohol 6 drachms.

Instantaneous Shutters.

The means by which light is cut off instantaneously, which means very quickly, are various, and many of them are very ingenious. Some of these shutters are behind the posterior combination in the lens, and are so graduated for other than instantaneous purposes as to give a shorter exposure to the sky than to the foreground. For my own part I prefer simplicity, and I use means in which I have been anticipated by Wilson and others. My cap is my shutter. Sometimes I use a book. With both I have succeeded, and naturally suppose others can do the same. I do not despise the ingenious shutter.

In very many cases, with all the preparations in a normal condition, as we suppose, success does not attend our manipulations. There is still, therefore, a yearning for some method more reliable. I have frequently succeeded in taking instantaneous positives, that could not be intensified into respectable negatives. But from a collodion positive we know that a collodion negative can very easily be prepared by copying. In this way many a well-valued view is obtained, which otherwise would have to be sacrificed. On such occasions, therefore, where there is the least doubt of success, it is advisable to develop with the ambrotype developer, containing nitrate of potassa, nitrate of silver, and free nitric acid—the latter, however, in very minute quantity. We shall thus probably obtain a good collodion positive on a melainotype or ferrotype plate. This is afterward carefully copied into a negative. In several instances I have obtained a tolerable effect by using solution of sulphate of iron without any acid.



Preparation of Albumenized Paper.
[pp. 194195.]

Albumen can be used either pure or diluted. With pure albumen the prints are very brilliant, but the paper is not so easily prepared. Take, for instance, the whites of twenty eggs, taking care to separate the yolk thoroughly, and place them in a graduated measure. Remove all the germs with a glass rod, and ascertain the number of ounces. Afterward pour the crude albumen into a clean basin, and add for every ounce ten grains of chloride of ammonium dissolved in the least quantity of distilled water. Beat the mixture into a thick, white froth by means of an egg-beater, and allow it to stand for ten minutes ; then remove the froth with a fork, and throw it upon a clean hair-sieve. Proceed in like manner with the residual fluid, until it has been completely converted into froth and strained through the sieve. Now leave the albumen to stand for a day or so, well covered up from dust; after which filter through a piece of sponge, and again allow the mixture to settle for a couple of days, and then pour off the supernatant liquid portion from the settings into the porcelain or gutta-percha dish for use.

The paper, as usual, must be of the finest quality, and marked or stamped on the back, before floating. Much more care is required in the successful management of laying paper on the salted albumen than upon the plain salting solution, for bubbles are more likely to be formed, and are less easily removed than in the former preparation. Besides this, if the paper be dry, and the weather also very dry, the albumen does not attach itself easily to the paper, and in this case, although a sheet has been thoroughly, floated, and without bubbles, the upper part of the sheet, when bung tip, allows the albumen to flow off, so that the film on the upper part is much thinner than on the lower part, and a number of irregular marks and curves are apt to be formed on the lower part. To obviate this, the sheet is suspended by its broadside, by which the distance between the upper and lower side is the least possible. The time of salting in this bath is from two minutes and a half to three minutes. Of course in all cases the time has to be reckoned from the moment the sheet lies uniformly and without bubbles on the surface of the solution.

In every operation of this nature it is well to have systematic arrangements. For this purpose I recommend the photographer to proceed as follows in the preparation of his drying-chamber. On the side of the room, behind the salting solution, and at an elevation of the eyes of the individual, screw oil a slip of wood a couple of inches wide and the length of the room. Supposing then the sheets are twenty-two inches long, then bore two holes twenty-one inches apart through the slip of wood; into the apertures insert corks, fitting firmly, and projecting about half an inch from the surface of the wood. Into the center of each of these corks insert the eye end of a steel needle inclined slightly upward. The sheets when raised by the two interior corners, and after draining, are hooked by the two upper corners upon the projecting  needles, which, before their insertion into the. corks, have to be varnished to prevent rusting and other troubles. When several rows of sheets have to be dried consentaneously the uppermost slip of wood must be the thickest, as, for instance, three inches, if there are three rows, one over the other; the second, two inches; and the last, one inch thick.

In proportion as the albumen accumulates on the lower border, it is removed with bibulous paper, until the papers finally are dry. They are then taken down and planished between rollers or otherwise, and piled away.


[pp. 200-208]

THE operation of printing is performed by the direct rays of the sun or by diffused light. Frames of various sizes are to be had of the dealers for this special purpose. These are oblong dishes, about two inches deep, with a pane of plate glass for the bottom, lying upon a ledge loosely. Upon this the negative is placed, collodion side upward, and over the negative the sensitized paper, albumen side downward. A piece of chamois leather, soft cloth or Canton flannel of the size of the pane of glass is placed over the paper carefully, so as to keep it in its position directly over the negative, and to form a sort of cushion when the folding doors, that come next, are fixed in their place. There is quite a knack in adjusting the leather so as not to produce any friction upon the negative, which would certainly injure if it were not varnished. The negative lies as near the middle of the pressure frame as can be, and in the same direction as to length. The folding doors are two thin flaps of wood joined by hinges in the middle, equal in size together, and lying horizontally to the pane of glass. This door is adjusted in its place over the cloth or leather in the following manner. Whilst the outstretched fingers of the left band are holding the paper and cloth in their places, without the slightest friction, the nearer flap is put in its place and held down by a gentle pressure, whilst the left hand now relinquishes its hold closes down the other flap. By means of strips of wood, an inch and a half wide, stretching across the frame and fixed on hinges on one side of the printing frame, and supplied with metallic springs beneath, each flap is pressed down and held in its place by m means of a hook on the other side. By such an arrangement it is evident that each folding door is independent of its neighbor, and by opening it the cloth over one half of the negative can be thrown back, the picture can be raised and examined, and again replaced without disturbing the relative position of the paper and negative. So arranged, the printing frame is now exposed to the sun, by rearing it on a shelf at the outside of the window right in front of this orb. The color of the paper will soon begin to change, and soon the whole picture will be apparent. Some negatives produce the best prints when exposed to a very powerful light; others on the contrary require to be printed slowly. A negative which is very dense will yield the best effect by exposing  the frame to diffused light ; whereas a very thin negative may be exposed to the full blaze of the sun, in order to be printed very quickly. The best prints are obtained from negatives that are neither too dense nor too thin. The frame is taken into a shaded corner of the room from. time to time, and one end of the print is examined in order to ascertain the progress of the operation. If the lights are still white, and the shades not yet bronzed in the slightest degree, the print is not yet finished. As a rule it may be concluded that this operation is complete when either the lights have become slightly tinged by reduction, or when bronzing is beginning to appear in any part of the shadows. In this case, take in the frame, and placing it on a table or shelf, remove the folding doors, then the cloth, and finally the print. Be careful not to expose the print to a strong light, otherwise the whites will be injured. Place it between the leaves of a book or in a drawer in the dark-room, until a sufficient quantity has accumulated for the next operation. An experienced printer will be able to obtain satisfactory results as far as circumstances will permit; but it is utterly impossible to force an interior negative to yield a superior print; a certain relation, a certain happy relation, (a remark that I have so many times repeated, but not too often,) must exist between lights, middle tones and shades, with a given density of the latter in order to secure normal prints and where this exists, it is the fault of the printer if he does not arrive at the maximum result of perfection.


In the dark-room, illumined by the yellow light of a lamp, or by that which passes through the orange-yellow non-actinic glass, examine the points separately, rejecting each in  which there is a decided failure, and cut off all extraneous parts that are certainly not required when mounted, allowing of course, always sufficient margin for the  final trimming. Next throw each print separately into a pail or tub of water, taking care that its surface comes in contact with the water, without the intervention of bubbles. Keep the prints in motion by turning them over and over again for the space of five minutes, and afterward take them out separately and immerse them in another tub of water in the same manner as before. The water from the first pail is poured into a large barrel or tank kept for this special purpose. Move the prints about as before for five minutes, and then proceed to the third pail in like manner. The water from the three pails is poured into the tank, and a tea-spoonful of common salt is added and dissolved by agitation with a wooden stirrer; after the subsidence of the deposit of chloride of silver, the refuse water is allowed to flow off into the sink by a stop-cock inserted within a couple of inches from the bottom of the tank.

Formula No 1. For the Toning Solution.
Chloride of gold, (pure,) . . . . . 1 grain.
Distilled water . . . . . . . . . 8 ounces. Carbonate of soda to neutralize the acidity.
Alcohol . . .. . . . . . . . 2 drachms.
Formula No. 2.
Double chloride of gold and potassium, 2 grains.
Distilled water . . . . . . . . . 3 ounces.
Carbonate of soda . . . . . . 35 grains.
Formula No. 3.
Chloride of gold . . . . . . . . I grain.
Distilled water . . . . . . . . . 8 ounces. Chalk to neutralize the acidity.
Chlorinetted lime .. . . . . . . 5 grains.
Alcohol . . . . . . . . . . . 2 drachms.

Formula YO. 4. Gold and Uranium.
 Chloride of gold, (pure,) . . . I grain.
No. 1. Distilled water . . . . . . . 4 ounces.
 Chalk to neutralize the acidity. Filter each
 Nitrate of uranium, . . . . I grain. and then Mix.
No. 2. Distilled water . . . . . . . 4 ounces.
 Chalk to neutralize the acidity.
  Formula No. 5.
Chloride of gold, . . . . . . 2 grains.
Distilled water . . . . . . . 8 ounces.
Phosphate of soda . . . . . . 100 grains. Neutralize with chalk.
Formula No. 6.
 Chloride of gold, (pure,) . . 2 grains,
 Distilled water, . . . . . 4 ounces.
No. 1. Carbonate of soda to neutralize the acidity,
 Phosphate of soda, . . . . 2 grains. Filter the latter
 Acetate of soda . . . . . . 2 grains. and mix.
 Nitrate of uranium, . . . . 2 grains.
No.  2. Distilled water, . . . . . 4 ounces.
 Chalk to neutralize the acidity.

The acidity of any of the above Solutions is neutralized as follows: In the first place throw into the solution a piece of blue litmus paper of the size of a ten-cent piece, its color will be turned red; now throw in either carbonate of soda or carbonate of lime until the blue color is restored. Carbonate of lime (chalk) has this advantage over carbonate of soda, it can be used without litmus paper, taking care only to throw in a superabundance, which does no harm, and can afterward be removed by filtration. I prefer preparing the double chloride of gold and calcium beforehand, and in quantity in a concentrated liquid form. In such a condition a few drops can be added to the toning bath in a moment, whenever it is found that the toning does not commence or proceed satisfactorily.
Pure chloride of gold is a deliquescent salt, is not easily crystallized, and when crystallized is not easily retained in this form. Its color is of a deep reddish color. But the chloride of gold, sold as such, is of a yellowish color, in a dry crystalline condition, and is Dot deliquescent; it is therefore not pure; it is probably in most cases a double chloride, either of gold and potassium, or of gold and sodium. These double salts are used in toning, as recommended in the above formulae ; but it must be remembered, that in buying such an article, double the quantity will be required, and of course you have to pay the price of gold for the soda or potassa in the mixture, which is poor economy.

With any of the preceding formulas baths may be formed which will produce rich tones. Formula No. 5 admits the substitution of citrate of soda, or acetate of soda for the phosphate. The first is the simplest, and I think the most rational; probably the third will please many; its tone is more of a sepia. The aim of the citrate, acetate, and phosphate is to produce a purple tone. The uranium bath produces a rich tone, still I do not think it superior to the simplest alkaline gold bath. Use the bath slightly warm, that is, at a temperature of 90' or 100'. Before the prints are introduced into the toning bath, pass them separately through hot water. Let the bath be sufficiently large to accommodate a number of prints side by side; turn them over continually; keep them in motion. The tone of the prints soon begins to change ; before it becomes of a slate blue, take each print out, wash in hot water, and immerse in the fixing bath.

Fixing Solution.

Hyposulphite of soda,  2 Ounces.
Water .. . . . . . . . . I ounces. Slightly warm.
Alcohol . . . . . . . . . 4 drachms.

The first effect of the toning bath is to change the color to a reddish line, and then finally back again. Move the prints about in this bath continually, and keep them in until the whites are perfectly clear when viewed by transmitted light, and the tone has been restored. Where the printing has been well performed, supposing the contrast in the negative to be right, the color of the deep shades is but very little changed in the fixing solution, and very soon returns to the proper tone. If the whites are full of gray spots when the prints are placed between the light and the eyes, it is a sign that the fixing is incomplete, and probably too that the prints during the washing and the toning have been too much exposed to a strong light. All operations, until the fixing is complete, ought to be performed in a room lighted by non-actinic rays.

When the tone of the picture and the transparency of the whites are satisfactory, remove the print from the fixing bath and immerse it in a tub of water. Do so with all of them, until the fixing operation is complete. The prints are now kept in motion for a few minutes in the water, in order to remove as much as possible of the fixing solution from their surface. They are then taken out and allowed to drain, and finally immersed in another tub of clean water, where they remain for a number of hours, taking care to move them about, and to turn them over frequently. The water in the washing operation can not be changed too frequently; in fact, it is by far the most desirable plan to have an arrangement by which the prints can be subjected to a running stream of water, which can easily be made in large cities supplied with water works.

The apparatus for this purpose is adjusted on pivots so as to rise and fall like the beam of a pair of scales, and it is put ill motion by the weight of the water itself. It consists,,, in the first place, of a trough of wood of any given appropriate length, as, for instance, three feet ; its breadth may be one foot, and its height the same. It is divided into two compartments in the middle, and supported on pivots in the middle of the base-board about six inches above the table or shelf on which it rests; by this means it has an oscillating motion or play of about twelve inches at either end, like a see-saw. This trough is placed so that the middle division is, when horizontal, immediately below the stop-cock; but when one is down and filled with water, and the other up and empty, it is evident that if the stop-cock be open, the water will flow into the empty compartment until this sinks, which it will do when the other is empty. Each compartment is supplied with a syphon, whose arch reaches to a plane nearly level with the top; the calibre of this syphon is somewhat greater than that of the ingress pipe furnished with the stop-cock. Now when either end becomes filled with water, the latter will rise higher than the arch of the syphon, which will then be filled with water. The longer arm of the syphon passes through the end of each compartment and discharges the water from its corresponding end quicker than the water is supplied to the other end by the stop-cock. By this expedient one end becomes alternately light and heavy, and thus produces a constant oscillation of the whole trough up and down. The prints to be washed are placed in these troughs as soon as they leave the fixing bath, and are thus kept in motion and supplied with fresh water for any length of time. Such a machine is called the

Self-Acting Photographic Washing-Machine.

When prints are thus treated an hour's washing will remove every trace of the hyposulphite of soda. They are then taken out one by one and pinned by one corner to slips of wood, or suspended on varnished hooks inserted into corks, as before described in the albumenizing process.

Mounting of Photographs.

Photographs may be cut out of the proper size and shape, either before they are starched or gummed or afterward. If before, the following is the mode of proceeding. Place a thick plate of glass before you on the table, oil which lay the photograph, picture side upward. Next place over this a heavy mat in such a position as to present the best appearance the print can receive. Holding the mat firmly in its place, by means of the first and second finger stretched far apart, with a sharp-pointed penknife cut along the edge of the mat through the paper to the glass all the distance from the end of the second finger to that of the first. If you stand to perform this operation (a position to be preferred to that of sitting) move gently round to the left, still holding the fingers firmly on the mat. Press upon the mat with the right hand, whilst the second finger advances to the position of the first, and this one is again stretched asunder to a new point along the edge of the mat. Now make another incision along the edge in perfect continuity with the first, and thus proceed to the termination. This act of cutting out the prints requires considerable dexterity in pressing the plate, and making the incision so that the terminal cut is a continuity of the commencement, and that the edge all round is clean and not dentated. Where the business is extensive, it is advisable to fix up a special mounting-table like that used by potters for the formation of utensils out of the plastic clay. Such a table can be turned by the feet on a vertical pedestal, allowing the operator to sit all the time. A whetstone or hone is a very necessary appendage to the mounting-table.

The prints are now turned over and brushed over with a strong solution of gum-arabic, a mixture of gum-arabic and gelatine, or what is still better, with a solution of patent starch or dextrine, such as is used on the back of post-stamps. Where a number of photographs are mounted upon the same paper, it is usual to brush them over on the back with the solution before they are cut out, and when dry to perform the operation just described. The starched surface is then made moist by going over it with a moist sponge. The print is now adjusted upon an appropriate mount and pressed accurately down by placing first a sheet of clean paper over the print, so that its edges overlap the latter, and then holding the first and second finger far apart and firmly on its surface, the print is pressed upon the cardboard by rubbing the space between the two fingers with a burnishing tool or With. the smooth handle of a tooth-brush. The fingers then assume different positions, and the burnishing is continued until the whole print is smoothly and evenly adherent to the Mounts beneath.

Photographs, after they have been starched, or moistened after starching, can be mounted much more quickly by first adjusting them to their place on the mounts, and then passing them beneath the rollers of a glazing or planishing machine. The two operations are then performed at one and the same time. This planishing is quite an improvement to a print; it is altogether superior to varnishing or glazing. The best rolling machines are those furnished with a horizontal bed, like that in a lithographic press. Still those that consist simply of a pair of rollers are very efficacious in producing decided improvements in stereographs or card-pictures.

Great care is required in keeping out all particles of sand from the starch or gum, for where these appear they produce protuberances on the photographs or apertures when the prints are submitted to pressure in the rolling-machines. It is therefore always necessary to remove them from the starched surface before it is placed on the cardboard, wherever such particles are discovered ; and to obviate the repetition of such troubles or diminish their number, it becomes the duty of the operator to cover his gum carefully up when it is not in use.

Mat to do with the Clippings of Prints.

Spoiled prints, soiled sensitized paper and the cuttings of pictures may as well be preserved as not, for the labor consists simply in placing them in some corner or box, instead of throwing them away. As soon as the stock is very large, they may be burnt in a clean stove and the ashes collected. These ashes contain silver, oxide of silver and other combinations of silver, together with the minerals in the paper, as, for instance, lime, etc. The ashes so constituted are pressed closely and firmly together into a Hessian crucible, then submitted to a powerful heat and thus reduced. Or these ashes may be mixed with the chloride of silver, obtained by precipitation of old baths or at the bottom of the tanks containing the refuse washing water. The mass is first well dried, then intimately mixed with about one half its weight of either carbonate of soda or potassa, and fused.

In large establishments the refuse silver salts, as well as the cuttings of paper, amount to quite a large quantity annually, and are sold for reduction to parties who make it their business. Where such an opportunity presents itself, it is more advantageous  to dispose of the unreduced refuse than to perform the operation of reduction one's self.

Mounting of Stereographs.

Stereoscopic negatives taken from nature contain two photographs which, when printed, are inverted, the left picture being where the right ought to be. Some photographers remedy this defect by cutting the negative in two in the middle, and then proceeding from the middle, right and left, two inches and three quarters, the residual slips are cut off on the ends and thrown aside. The two negatives are now placed upon a thin glass stereoscopic slide, perfectly clean, and side by side in juxtaposition, but inverted, so that the right-side negative is placed on the left side. By means of gummed or glued ribbon on the upper edge,;, these negatives are held firmly on the slide beneath. The negatives being so arranged, the prints will have the right position, and require only to be pared at the top and bottom previous to mounting. For this purpose a piece of glass, with rectangular corners and ground edges, five inches long and two inches and a half wide, is placed upon the prints on  the mounting table or slab of glass; with a sharp penknife go round the edges, taking care to press the glass form firmly on the prints. In this way the  pair of stereographs will be cut out in one piece ready for gumming and mounting. Copies of stereographs (if taken with a single orthoscopic lens) do not require the negative to be prepared as above described; the requisite inversion exists without it.

But in many instances the negative is not prepared at all in this manner for printing, but left in its natural or unaltered condition. In this case (and it is probably the easiest method of proceeding) the glass form is laid upon the inverted print, and the combined prints are cut out; after which another glass form of exactly half the size is laid upon one end of the combined prints, which are then cut asunder. The larger glass form has a notch on the top and. bottom edge in the middle; these notches are placed on the middle line of the print, and serve thus to direct its position. If this middle or dividing line between the two prints has considerable width, which is sometimes the case, the glass form must be in proportion longer; but the smaller form retains its size of two inches and a half. Stereographs of groups and of architectural objects are frequently cut out with rounded corners, sometimes on the top only, and sometimes both on the top and bottom. For this purpose you must prepare for yourself appropriate forms of glass, by grinding down the corners on a grindstone, or you can cut out the requisite shaped mats in brass. Those of glass are by far the easiest to construct.

Mounts for stereographs of various shades of color can be had of the dealers ; these, being cut by machinery, are neater and cheaper than those you can make yourself from cardboard. If you do not possess the power, that is, have not cultivated the faculty of seeing stereoscopically without an instrument, you must be very careful not to invert the right and left side pictures between the cutting and mounting It is well to be provided with two small boxes, one marked left and the other right, into which the corresponding prints can be thrown as soon as they are prepared for mounting. The mode of pasting, adjusting to position, and passing beneath the roller is  the same with the stereograph as  that with the ordinary photograph, which has been already described.


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