The Art and Practice of Silver Printing

Another method of purifying the solution is by adding a few drops of hydrochloric (muriatic) acid to it. Chloride of silver is formed, and when well shaken up, carries down with it most of the organic matter, but leaves the bath acid from the formation of nitric acid.[13] This must be neutralized unless a little silver carbonate is left at the bottom of the bottle as described at page 20. A camphor solution may also be added for the same purpose. Make a saturated solution of camphor in spirits of wine, and add a couple of drachms to the solution, and shake well up. The camphor will collect the albumen, and it can be filtered out. In case the first dose does not decolourize it, another one must be added.

Another plan is to add potassium permanganate (permanganate of potash) to it, till such time as the solution takes a faint permanent rose tint. The theory is that the organic matter is oxidized by the oxygen liberated from the permanganate, and falls to the bottom. It is not strictly true, however, and the solution will never be as free from organic matter as when the other methods are employed.

The final and best method is to add a small quantity of sodium carbonate (say 5 grains), and expose it to daylight. When the organic matter becomes oxidized at the expense of the silver nitrate, the metallic silver with the oxidized organic matter will fall to the bottom. This plan answers admirably when time is no object, but in dull weather the action is slow. When once the precipitation fairly commences it goes on quickly, and if a little freshly precipitated metallic silver be left at bottom of the bottle the action is much more rapid. This is a wrinkle worth remembering in all photographic operations where precipitation is resorted to.

We have hitherto supposed that the only contamination of the bath is organic matter, but it must be borne in mind that each sheet of paper floated on the solution transfers a certain amount of nitrate of the alkali[14] with which the albumen is salted.

It will thus be seen that in an old bath there will be no need to add the soluble nitrates given in page 17, since they will be already formed. When they are in excess the best plan is to precipitate the silver by some means,[15] but we select one which is easy of application, since it requires no watching. Evaporate the solution to half its bulk, and slightly acidify it with nitric acid (10 drops to the pint of solution will suffice); throw some ordinary granulated zinc into the jar or bottle containing it; the silver will now be rapidly thrown down in the metallic state, and in the course of two or three hours the action will be complete. Next carefully pour off all the fluid as close as possible to the residue. Pick out all the lumps of zinc, and add a little dilute hydrochloric acid to dissolve up all the small particles of zinc which may be amongst the precipitated silver. Filter the solution away, and wash the residue once or twice with water. Take out the filter paper, and dry it before a fire, or in an oven, and then detach the silver, and transfer it to a small crucible, which place, with its contents, over a Bunsen burner or spirit lamp flame till it is red hot. The heat will destroy all organic matter, leaving a residue of carbonous matter behind, which, after subsequent operations, will be eliminated by filtration. Next cover the silver with nitric acid,[16] and in an evaporating dish slightly warm it over a spirit lamp or Bunsen burner. Red fumes will appear, and when all action has ceased, more acid must be added till such a time that very nearly (but not quite) all the silver is dissolved up. Then evaporate off all the fluid and allow it to cool, when water can be added to such an extent that it is over strength for the bath. Now measure the whole bulk of the solution in a glass measure, and test by the argentometer for strength. An argentometer is, in reality, an instrument for taking the specific gravity of a liquid. It is as shown in the figure. A B is a glass tube, inside of which is a graduated scale showing grains; C is a hollow glass cylinder, which has a little glass ball filled with mercury. When immersed in water, the instrument sinks till the scale reads 0—that is, A B is deeply immersed. When any soluble salt is dissolved in the water, the stem rises further. If the soluble salt be silver nitrate, the scale is made to read grains per ounce. It is then evident, if the bath contains any other soluble salt besides the nitrate of silver, the readings will be untrustworthy. Supposing you have a total quantity of 10¹/₄ ounces of solution, and the argentometer tells you it is of a strength of 105 grains to the ounce, you must make a small calculation to see how much water you must add. In 10¹/₄ounces of solution there will be 10¹/₄ × 105 or 1076¹/₄ grains of silver nitrate. If you want to make the bath 40 grains to the ounce, you must divide this quantity by 40, which is very nearly 27. The original amount of fluid (10¹/₄ ounces), when deducted from this number of (27) ounces, will give you the amount (16³/₄ ounces) of water that is to be added to give you a bath of the required strength. When the water is added, the solution should be filtered from the carbonaceous matter, and the bath, after neutralizing with sodium carbonate, will be ready for use.

CHAPTER V.
APPLYING THE SILVERING SOLUTION TO THE ALBUMENIZED PAPER.

As each piece of paper takes somewhere about five minutes to sensitize and hang up to dry, it is evident that the larger the piece of paper sensitised the greater will be the saving in time in this operation. Practically a whole sheet of paper, which is about 22 inches by 18, is the maximum ordinary size, whilst it may be convenient to float a piece as small as 3¹/₄ by 4¹/₄. There is not much difficulty in floating either one or the other if ordinary care be taken, but it is no use disguising the fact that large sheets are sometimes faultily sensitized even by experienced hands, if the solution be not in a proper state. The great enemy to success is the formation of bubbles on the surface of the solution, and if it be at all contaminated with organic matter they are more liable to be met with than if the bath be new. It may be taken as a maxim that no paper should be floated if, to commence with, the bath be not purified. A flat dish of about 2¹/₂inches in height, and an inch larger in breadth and length than the paper to be floated, is used, and the solution poured in to a depth of ¹/₂ inch. The paper is grasped by the two hands as shown at page 10, so that a convex albumen surface is formed downwards, which is placed diagonally across the dish and lowered on to the surface of the solution; the hands are at the same time separated outwards, so that the whole surface of the paper is caused to float on it without any arrest. By this means all air is forced out before the paper, and no bubbles should be beneath. To make assurance double sure, the paper is raised from the corners which were not grasped by the hands, and if by any chance a small bubble should be found, it is immediately broken by the point of a clean quill pen or glass rod. Before floating the paper the surface of the solution should be examined for scum or bubbles, both of which may be removed by passing a strip of clean blotting-paper across it. The dish employed should be scrupulously clean, and in cold weather it is a good plan to warm both it and the solution before the fire previous to use. In warm weather, the albumen of the paper may be in a very horny condition, which increases the liability to form bubbles. The writers have found that if the sheet of paper be exposed to the steam passing from a kettle of boiling water for a few seconds (moving it so that every portion shall come in contact with it) just before sensitising, the surface becomes more tractable, and in a better condition for sensitizing; keeping the paper in a moist atmosphere effects the same end.

The length of time for floating the paper depends on the subjects to be printed, but, as a rule, three minutes with the 50-grain bath will be found to answer for the majority of negatives. When the proper time has elapsed, a corner of the paper is raised from the solution by means of a glass rod, and grasped by the thumb and forefinger of the right hand. It is then raised very slowly from off the solution till another corner is clear, when that is grasped by the forefinger and thumb of the left hand; and it is finally withdrawn entirely, and drained a minute from the lowest corner into the dish. It is next hung up to dry by a corner which should be fastened to an American clip (fig. 7) suspended from a line stretched across the dark room, taking care to keep the corner which last left the solution the lowest. A piece of clean blotting-paper about one inch long by ¹/₂ an inch wide is brought in contact with this latter corner, and adheres to it from the moisture. This collects the draining from the paper whilst drying, and prevents a loss of silver, since it can subsequently be detached and placed amongst the residues for burning.

There is another mode of floating large sheets of paper, which is sometimes recommended. One corner is turned up about a quarter of an inch. This is held by the forefinger and thumb of the left hand, and the opposite corner of the diagonal held by the right hand. The first corner is brought on the solution near the opposite corner of the dish to that towards which it will eventually be near. The sheet, having assumed a convex form, is drawn by the left hand across the dish, the right hand being gradually turned to allow the whole surface to come slowly in contact with the solution. Air-bubbles are said to be avoided by this means, though for our own part we see no practical advantage in it over the last method.

Some operators also, when lifting the paper from the dish, pass it over a glass rod placed as in the figure, in order to get rid of all superfluous fluid from the surface. This is a poor substitute for withdrawing the paper slowly from the dish, since capillary attraction is much more effective and even in its action than this rude mechanical means. By those who do not possess patience, however, it may be tried. Some practical photographers also "blot off" the excess of silver, but this is a dangerous practice unless there is a certainty that no "anti-chlor" has been used in preparing the blotting-paper. For our own part we recommend the usual mode of draining the paper. When surface dry, it can be dried in a drying box. The following is a kind which has been adopted by one eminent photographer, and is excellent in principle.

Over a flat and closed galvanized iron bath erect a cupboard. Fig. 10 gives the elevation, and fig. 11 the section. A is the bath, D the cupboard, which may conveniently be closed with a roller shutter,[17] B, passing over c c, and is weighted by a bar of lead, so as to nearly balance the weight of the shutter when closed. A couple of Bunsen gas-burners, E E, heat the water in A; the steam generated is carried up the flue F, which also carries off the products of the combustion of the gas. The paper may be suspended from laths tacked at the top of the cupboard by means of American clips.

CHAPTER VI.
WASHED SENSITIVE PAPER.

For some classes of work sensitized paper may be washed with advantage previous to drying, and there is much economy in this plan, particularly in hot weather, since it keeps of a purer white for a much longer period than where the silver nitrate is allowed to dry on the surface. It may not be out of place to call attention to the action of silver nitrate on the paper. If a stick of lunar caustic be applied to the skin when dried, there is a peculiar burning effect produced, and even in the dark the cuticle becomes discoloured, though not black. In the albumenized paper we have albumen and the gelatine sizing, and these substances behave somewhat like the skin. The gelatine particularly will become oxidized at the expense of the silver, a reddish organic oxide being formed; and again, if the silver nitrate be alkaline or strictly neutral, we have the same action occurring as when we precipitate metallic silver by means of an alkali, and an organic body such as sugar of milk. The gelatine takes the place of the latter. When the free silver nitrate is removed, the tendency for the spontaneous darkening of the paper is much diminished, since the chloride and albuminate of silver are much less readily reduced than the nitrate. The following plan is adopted for washing the paper:—The paper, after floating, is drawn twice rapidly through a dish of rain or distilled water, and, unless some other substance which can absorb chlorine be added to the last wash water, care should be taken not to soak out all the free nitrate, as then the paper would produce flat prints. It is then hung up to dry as before. Immediately before use it must be fumed with ammonia, in order that the prints may be "plucky," and free from that peculiar speckiness of surface which is known to the silver printer as "measles." We can readily trace the "measles" to their source. Suppose all free silver nitrate is washed away, and the paper be then exposed to light, the chloride is rapidly converted into subchloride, and chlorine is given off (see page 5); if there be nothing to absorb it at once it will attack the albuminate, which is blackened at the same time, and fresh chloride will be formed in little minute spots. These discolour, and are of different tint to the rest of the print, and give rise to the appearance of measles. This, of course, is not so marked when a little free silver nitrate is left in the paper; but as what is removed is principally removed from the surface, it may still be unpleasantly discernible. Fuming obviates it entirely if properly performed, for chlorine and ammonia combine to form finally ammonium chloride, a neutral and inactive salt.

Any other chlorine absorber may be substituted; thus citric acid, potassium nitrite, and many others are effective, and cause vigorous prints to be produced. Perhaps the easiest way of giving the paper the necessary amount of ammonia is that recommended by Colonel Wortley. This is to place overnight the pads of the printing-frame, if they be of felt, into a closed box in which is placed a saucer containing a couple of drachms of liquor ammoniæ, and to withdraw them as required for the printing-frames. The pads will be thoroughly impregnated with the vapour of ammonia, and a couple or more prints, in succession, may be made before it is necessary to change them.

The ordinary method of fuming is that used in America. Hearn describes a box, which is very convenient and simple in construction. He says: "Take any common wooden box, large enough for the purpose, and make a door of suitable size for it, which, when shut, will totally exclude all light. Make a false bottom in this about six inches, or so, from the real one, and perforate it with holes of about the same size that a gimlet would make. These holes should be very numerous, and at the centre there should be, if anything, a smaller number of them, because the saucer containing the liquor ammonia is generally placed at the centre of the real bottom of the box."

For our own part we dislike the false bottom as constructed, and recommend one of fine gauze, and, instead of placing half-an-ounce of ammonia in the saucer as Hearn directs, we prefer to soak half-a-dozen sheets of blotting-paper in ammonium chloride solution, about 20 grains to the ounce, and the same number of sheets soaked in lime water; one sheet of each are placed together, and ammonia is liberated by double decomposition; calcium chloride being also formed.

This method is excellent in hot, dry weather, since it imparts a certain amount of moisture to the paper. In damp weather it is a good plan to dry the vapour by sprinkling on the gauze calcium chloride, which will rapidly absorb the aqueous vapour, and will allow the ammonia to pass on unimpeded. The sheets of paper are held at the top of the box by American clips, suspended from laths about three inches apart, and it is not a bad plan to fasten a lath on to their bottom edge by the same means, to do away with their curling. To fume a single piece of paper it may be pinned up to the inside of the top of the lid of a box, and a drachm of ammonia sprinkled on cotton wool distributed at the bottom. The point to be attended to is that the fuming shall be even, and it is evident that the ammonia should rise equally from any part of the bottom of the box. In the plan of the box given above, the bottom of the sheet is apt to get a little more ammonia than the top. The time of fuming depends on so many things that a rule can scarcely be given for it; twenty minutes may be considered about the extreme limit.

If this sensitizing bath be acid, the time must evidently be longer than when it is strictly neutral or slightly alkaline; and if the negative be hard, it will require to be less fumed than if it be of a weak nature, since the action of ammonia is to cause rapid darkening in the deep shadows. In hot weather the fuming should be shorter than in cold, since the ammonia volatilizes much more rapidly when the temperature is high. On the whole, we recommend Colonel Wortley's plan of fuming the pads in preference to fuming the paper.

Another mode of preserving the paper from discolouration is to add citric acid to the printing bath, which is effective owing to the fact given at page 32. The following formula is a good one, and has answered with the writer. It is—

The paper is floated for the ordinary length of time, when it is dried thoroughly and placed between sheets of pure blotting-paper. It will keep in its pristine state for months, if excluded from the air. It is better to fume this paper strongly before use, or the toning becomes a difficult matter.

Ordinary sensitized paper may be preserved for a considerable time if, when dry, it is placed between sheets of blotting-paper saturated with a solution of carbonate of soda, and dried.

Washed sensitized paper is also improved in sensitiveness by floating it for a few seconds on—

It can be fumed, when dried, in the usual manner.

In the Year-Book of Photography for 1880 Mr. A. Borland recommends the following modification:—

He floats the paper on nitrate of silver, as usual, and after it has drained surface dry, blots off any drops that may remain at the edges, and then floats the back of the paper for about three minutes on the following bath:—

This is rendered slightly acid by a little solution of freshly prepared citric acid in water. The degree of acidity is regulated by litmus paper (the blue specimen), which should be slightly reddened by it. After this solution has been mixed about ten minutes, it is filtered, and the paper floated. Mr. Borland says the paper keeps well, and prints the same as ordinary paper, and any tone may be produced.

CHAPTER VII.
CUTTING PAPER.

We have often come across operators who have no really definite plan on which they cut up their paper for a day's work, and they have little idea of the most economical place of dividing the sheets. The following remarks by Mr. Hearn, which appeared in the Photographic News, 1874, will be useful to the printer, and, being so extremely well described, we take the liberty of reproducing them.

"In cutting up the paper for printing, due regard should be given to the materials employed. In the first place, the fingers should be free from anything that will stain or soil the paper, and they should never touch the silvered side, but always the back. The hands should be perfectly dry, free even from any perspiration, for if this is not strictly regarded in the handling of the paper, 'finger stains' will appear on those parts of the paper with which the fingers come in contact. To guard against this, a rough towel should be suspended in a convenient place, and the hands wiped upon it as often as may be found necessary—say once in every five or ten minutes. An ivory newspaper cutter, about eight inches long and an inch wide, together with a suitable sized pair of shears, will be all of the instruments necessary.

"In cutting the paper for very large prints, such as 13 by 16, 14 by 18, 16 by 20, &c., the beginner had best (to obtain the right size) lay over the sensitive paper the proper sized mat that is to be placed over the print when finished, and then cut accordingly. Considerable paper can be saved in this way, and printed in card size.

"There should always be an assortment of different sized mats in the printing room; one of each size will do, which should be kept expressly for this purpose.

"In cutting the paper for an 11 by 14 print, the length of the sheet is generally placed before the printer, and the paper bent over to the further edge of the sheet, and then creased, and thus cut into two equal pieces, one of which can be used for the contemplated print. I would recommend that instead of taking exactly one half of the sheet of paper, as described above, to take about an inch more than the half, so as to allow for any slight tear that may happen along the edges of the paper during the washing, toning, &c., and also so as to be sure of having the paper wide enough for the different sized mats.

"I have seen some nice prints printed upon the exact half of a sheet of paper, which, when taken from the final washing (and the edges trimmed, being slightly torn), were then too narrow to be covered with the proper sized mats, and had to be rejected; whereas, if in cutting this paper allowance had been made for this final trimming, the prints would have been saved. The rest of the sheet can be cut very well into sixteen or eighteen carte pieces.

"In cutting cabinets out of a sheet, fifteen is all that can very well be obtained, and to get that number lay the sheet on a wide table, or printing bench (with the length of it running from right to left), and divide it into three equal parts. By laying the cabinet glass on these strips of paper, and cutting the paper a little wider than the glass, five cabinets can be obtained from each strip, and fifteen out of the whole. These pieces will be plenty large enough, both in length and width; besides, this is a very convenient and economical way to cut the paper without waste.

"By a glance at the cut (fig. 12) it will be seen that the size of the pieces will be 4²/₅ by 6 inches, and consequently there will be more room for the width than there will be for the length. The edges of the width side of the paper can be trimmed a little, as there is usually some little tear, or some other defect, that can thus advantageously be got rid of. Often, when there are only a few cabinets to be printed, I take a quarter-sheet, and bend over the length of it to about three-quarters of an inch of the opposite side, crease it, and then cut with the paper-knife. You thus obtain a large and small piece; the smaller one of these can be cut into four cards, and the larger one can be cut in two, and thus obtain two generous size cabinets; or the printer can use the larger of the two pieces for printing the 4 by 4 size. This is the way I obtain my 4 by 4 pieces when I wish them.

"The beginner must remember that in bending over the length of a sheet of paper 18 by 22 inches in size, the divided paper will be 11 by 18 inches in size, which is termed, in the language of the printing room, half-sheet.

"To obtain the quarter-sheet, the length of the half-sheet is cut equally in two pieces, and then the size will be 9 by 11 inches.

"A glance at fig. 13 will show that either a generous size 4 by 4, or a couple of nice cabinet pieces, together with four cartes, can be easily obtained from a quarter-sheet.

"To obtain thirty-two cartes, quarter the sheet, and divide each quarter into eight equal pieces.

"To obtain thirty-six pieces out of a sheet, it is necessary, for convenience, to first quarter it, and then divide it into three equal strips (fig. 14) taken from the length of the paper. The pieces, as thus cut, will measure 3²/₃ by 9 inches, which will answer admirably for the stereoscopic size. Each one of these strips of paper can be cut into three good sized cartes, making nine out of a quarter, and thirty-six out of a whole sheet.

"Forty-two cartes can be obtained very neatly by laying the sheet before you (fig. 4), and dividing the length into seven equal parts; when done, each strip should measure 3¹/₇ by 18 inches in size. The whole number of pieces will be forty-two. It will be seen that the size of the carte pieces (3 by 3¹/₇ inches) only allows very little room for waste paper in trimming after printing, and thus it will be found necessary to exercise some care in placing these pieces on the negative for printing.

"In making out the above, I have considered the sheet of paper to be 18 by 22 inches in size, but it is seldom that the sheet measures exactly this, for the length often measures from one quarter to one inch more, but never less, while the width is invariably the same. When this is the case, a little better margin is allowed in cutting the sheet up, which is a good thing, especially when a large number of small pieces are to be obtained from the sheet. Forty-two pieces is all that should be obtained from a sheet of paper which measures 18 by 22 (or 18 by 22¹/₂, &c.) inches, because the pieces of paper are now as small as they should be with safe results to the prints, on account of bad edges, &c., which it is often necessary to trim after printing. There is a way to obtain forty-eight, and even fifty-two pieces of paper from the sheet, but I would not advise any of my readers to try to obtain that quantity, as there are many disadvantages connected with it that more than neutralize the benefits. The paper is sometimes cut up to the exact carte size, and then printed up as it is, thus saving the trimming of the prints after printing. This is, perhaps (?), a good way, but for the beginner it is very risky, because the paper will have to be placed exactly on the negative, or else the print will be worthless. Even to the experienced printer this is very difficult, because the greatest care and skill are required to do it as it should be done; then the inexperienced printer could not hope to do it successfully."

CHAPTER VIII.
PRINTING-FRAMES.

There are a variety of printing-frames in the market, each of which may have something to recommend it; and yet, as a rule, the simpler and more uniform the frames are, the more handy are they for the printer, since he rapidly becomes accustomed to handling them, and knows their peculiarities. The simplest pattern is one introduced by Meagher, as shown in fig. 16. The negative rests on india-rubber strips which line a framework of its exact size, and a folding back, as shown, covers it. The paper is pressed on to the negative by a pad, and the back on that by means of two brass springs. This is a very excellent pattern for cabinet pictures and cartes, but we can scarcely recommend it for anything larger, since even if it were possible to supply sufficient pressure to secure proper contact of the paper, the negative would be in danger of being cracked.

For all sizes above cabinet, the printing frame as given in the figure is the best. The construction will be seen at once. In the front part of the frame is a piece of thick plate glass (depending for its thickness on the size of the frame). On this the negative rests, and over this again are the necessary pads and backboard, which is clamped down by means of two cross-bars, on which springs are fixed. An increase of pressure may be given by increasing the thickness of the pad (which may consist of smooth felt) next the negative, or by sheets of thick blotting-paper quite free from all folding marks.

Sometimes the back of the frame is hinged in three pieces,[18] and this is almost essential for large prints (say 2 feet by 1 foot 6 inches), since every part of the picture should be capable of examination during the progress in printing. With a simple single hinged backboard this is impossible.

When large negatives are to be printed, the plate glass front should always have at least an inch clear all round. For smaller negatives (say 12 by 10 and under) half-an-inch clear is sufficient. This allows a certain latitude in the position of the negative, and enables the fingers to get at the paper without inconvenience. In the frames in which the front of the negative is unsupported this cannot be the case, and for this reason (as well as those given above) they are not recommended for large prints.

CHAPTER IX.
PREPARING A LANDSCAPE NEGATIVE FOR PRINTING.

Landscape negatives are rarely ever in perfect harmony for printing, and much may be done by judicious doctoring of the best of negatives to secure the best of prints. With moderate negatives it is absolutely essential that they should be improved. Let us take the example of a hard landscape negative, which if printed so that the deep shades should show detail, would show none in the high lights.

A piece of thin tissue paper (the kind known as papier minerale is the best), of the size of the negative, is damped evenly with a sponge, and carefully pasted on the back of the negative. The negative is then held up to the light, and the high lights carefully traced with a faint line by means of a pencil. These are then cut out by means of a sharp penknife, and a trial print taken in the shade. If it be found that the shadows still print too deeply when the detail in the high light is visible, another thickness of tissue paper may be applied, cutting out this time, perhaps, the high lights and the half tones. Another trial print will show whether the object is attained. If still not satisfactory, crayon in powder from the scrapings of a stick of crayon, or blacklead, may be applied by a stump to the parts requiring it. It may happen that the effects of the tissue paper may be seen in the print by the light penetrating beneath it, and causing the edges of the shadows to print too dark. In this case, which may arise from the negative being taken on a thin glass plate, the parts covering the high lights, and which were cut out, should be indented with a jagged edge such as this, the dotted line showing where the cut would come if it had been cut out in a clean sharp line. Another mode which we have sometimes found successful, though care is required in employing it, is to coat the back of the plate with a very dilute emulsion of a quarter the ordinary consistency, then to expose it, through the negative, and develop with one of the ordinary alkaline developers (we prefer the ferrous oxalate),[19] and then fix. This last film may be protected with a layer of albumen 1 part of albumen to 25 parts of water. By this means the shadows become subdued and the contrasts diminished, and there is no danger of any sharp demarcations in the shades being apparent.

There is one way of improving a hard negative, if taken on a gelatine plate, which would probably be dangerous in the hands of a novice, but which is most effective when used with skill and judgment, but must be applied before the plate is varnished. One of the most popular methods of reducing the density of an over-intensified gelatine negative is with a very weak solution of perchloride of iron. The writers have found that the reducing agent may be applied locally. Let us suppose the case of a figure in a landscape in a light dress, which produces a white patch in the print. The negative should be placed in a dish of water, then lifted up until the part to be reduced is just above the level of the water; a solution of perchloride of iron should then be applied to the part with a camel's-hair pencil, care being taken that it does not spread over the edges or run down the negative. When this is found to be taking place, the plate should be allowed to fall into the water; it can then be lifted again, and the operation proceeded with. It is not easy to give any strength for the solution of perchloride of iron, but it is best to begin weak, and strengthen as required. A saturated solution has been used in an obstinate case without any mischief being done, but this required very careful watching.

For landscapes, Mr. England has successfully used a strong solution of cyanide of potassium with the same object. He moistens the parts of the gelatine plates which require reduction with water applied by a paint-brush, and afterwards, with another, applies the cyanide. The reduction can be watched as it progresses, and by a judicious use of the brush no sharp line of demarcation between the reduced and unaltered parts is visible.

With a thin negative the tissue paper may be applied as before, only in this case the shadows are left bare, the half tones have one thickness of tissue paper over them, the highest lights two or three. An emulsion may be used in this case as well, only instead of fixing the transparency which is at the back, the precipitated silver is dissolved away by nitric acid, and the developer applied again. By this means, the density in the high lights may be doubled if required. It must again be repeated, that in all cases the use of emulsion requires great care, seeing that if any get on the varnished surface, markings are sure to occur. It sometimes happens, especially with gelatine plates, that the corners of one side of a negative print too dark. This is very visible in sky and sea pictures. The careful application of blacklead on the tissue paper on the back of the plate may often save a beautiful negative that would be otherwise useless.

In most landscape negatives there is a want of atmosphere (by which we mean the haze always present in the air) in the distance and middle distances, and we have found that by applying one piece of tissue-paper to the back of the negative to cover the middle distance and distances, and another to cover the distance alone, atmospheric effect is produced. The effect of atmosphere is usually shown by grey tones as compared with those of the foreground, and the greyer they are the more distant should the objects be away in nature. This effect is accomplished by the tissue-paper. It must, however, be remembered that the lights of distant objects are greyer than those of the foreground, hence the tissue paper must be used with judgment to prevent the distant lights from appearing too white. This sometimes is effected by giving the lights in the foreground a covering of tissue paper. We very much doubt if there exists any landscape negative which would not be improved by the use of tissue paper, since photography often tends to do away with atmosphere. We have, in some cases, strengthened the high lights on the film side with the paint-brush and Prussian blue. This requires skill, and should be done very sparingly. It may be objected that when these artifices are resorted to, that the photograph must of necessity fail in regard to truthfulness. The answer to this objection is quite easy to give. If a photograph were true in itself, they should never be resorted to, but since it always falls short of the truth, it is quite legitimate to give it the effect that a perfect process would do, by which we mean one in which the intensity of the negative is exactly proportional to the intensity of the light producing it.

It has been shown in the Photographic News of 1877, that the gradations of a negative are never perfect, and the use of the tissue paper, &c., makes it more nearly in accord with nature.

These remarks, of course, have reference only to what we might call "a good printing negative;" the advisability of doctoring poor negatives is scarcely open to argument. Improve as much as you like, but be very careful not to overdo it.

CHAPTER X.
PRINTING THE LANDSCAPE PICTURE.

A trial print from a negative should first of all be taken, to enable the operator to gauge as to how much is required to be done to it. A piece of sensitized paper of the exact size of the plate is taken and examined by transmitted light in the dark room. If there be any appearance of markings due to bubbles, or of star-like metallic spots, probably due to small particles of iron being in the albumen, it need not be rejected altogether. Should there be any of these defects, the sheet should be placed on one side to cut up into smaller sizes. We will suppose that we are going to print a 15 by 12 negative. A strong frame (of the description given at page 44) must be employed, and the thick plate glass carefully freed from all dust, grit, or stains. The back of the negative is then placed in contact with it, so as to occupy the centre of the frame. The piece of sensitive paper is placed over it, and the back placed loosely over it, and is then carried face downward into the place where the printing is to be done, and the frame is placed face downwards on the floor, and left for a few minutes. By this artifice the paper takes the same degree of humidity as the atmosphere, and there will be no danger of any cockling, and consequent (as it is termed) want of contact, between the paper and the negative. This is only necessary when there is any very great difference in the temperature of the drying room and the place where the prints are to be exposed, and in some establishments the difficulty is met by carrying the whole supply of paper in a closed box into the latter place, and allowing it to absorb any moisture that it can take up. In any case, the paper is next to be placed in absolute contact with the negative, and we strongly recommend the use of sheets of blotting-paper cut to the proper size (about four thicknesses will be sufficient), and backed by a thick pad of closely woven and very smooth felt. These latter are rather expensive, but are very durable if ordinary care be taken of them. The blotting-paper is useful in causing contact, and also because any accidental presence of silver nitrate solution on the back of the sensitive paper is immediately detected, and there is, consequently, no danger of carrying it to another print and spoiling it, which it might do were it absorbed by the felt pad.

The back of the frame is then placed in situ, and the hinged cross-piece brought down and secured by the fasteners. If the springs be sufficiently strong, the film of the negative should now be in absolute contact with the sensitive paper. If there be any grit on the plate glass, or adhering to the back of the negative, it is highly probable that the glass plate will crack, and if the plate on which the negative is taken be very curved,[20] the same disaster may be expected. Suppose the day to be bright, and the negative fairly dense, the frame may be placed for the trial print facing away from the sun (if there be any) so that it receives merely skylight, and no direct rays. When the transparent parts of the negative seem to have taken a fairly black or brown colour, the print should be examined. In practice we have found (supposing the printing room be away from the dark room) that a cloth of thin yellow calico is a useful adjunct during the examination. The cloth is large enough to cover the frame and also the head of the operator. One half of the back is loosened and raised, the half pieces are pulled back, and the paper will probably be found adhering to the negative, and may require a little manœuvring to separate it. A very thin slip (of the size of a toothpick) of soft wood, sharpened at one end, is a good implement to employ, as by inserting it the paper can be separated at one corner, and then be raised by the fingers. We have seen some printers blow against the paper, as if they were separating the leaves of a book from one another, but this method is to be deprecated, since particles of saliva are apt to be carried on to the paper with the breath, and to cause spots, which often appear unaccountable. Should the print appear slightly deeper than it is required to remain, it is probably ready to be withdrawn from the action of light, but the remaining half of the paper must next be examined to see whether such is the case. To do this the first half of the pressure-board of the frame which is loose must be pressed down once more into position, the frame reversed end for end, and the other half of the board opened.

If the print is large (say 15 by 12) it is not advisable to look at much of it at once, or for a longer time than can be avoided. It constantly happens that on a warm day the paper contracts during the short time necessary for a proper examination of the print; the consequence is, that the paper does not fall on the same place on the negative when reflected, and the result is a double print on the paper.

The printing being judged to be complete, the paper is withdrawn by taking off pressure-board and pads, and put away for the further operations of toning and fixing. In one establishment we are acquainted with, the prints when taken from the frame are placed in a box the lid of which is pierced by a hole covered with a dark cloth; whilst others keep them in a press of blotting-paper. The great point to attend to, however, is to keep them away from all actinic light; and we should say, further, from all light, since darkened silver chloride becomes oxidized in light which is usually considered to be non-actinic. No doubt every printer is aware that the prints produced from the same negative and on the same sample of albumenised paper similarly sensitized vary considerably in richness and depth on different days. For instance, when the light is bad, and when, consequently, the printing takes a long time, the colour of the darkened surface will be found to be much duller than on a day when the light is powerful. Silver albuminate is much less sensitive to feeble light, whilst in bright light the difference in sensitiveness is not nearly so marked, and this may account in a certain degree for the difference; but if any one takes the trouble to expose sensitised albumenized paper to bright light so as to darken, and then to cover up half, leaving the other half to be exposed to the light coming through ruby-glass, it will be found that there is a difference in colour between the two portions, and on toning the differences will be still more marked. In dull weather the red and yellow rays bear a greater proportion to the blue and violet rays (all of which enter into the composition of white light) than they do on a bright day. It is the blue and violet rays that reduce the silver chloride to the state of sub-chloride, and then oxidize the latter; yet it must be remembered that the red and yellow also oxidize the sub-chloride without being able primarily to produce it. Hence on a bright day, when the printing is quick, the red and yellow rays have but little time to do any work, whilst on a dull day they have plenty of opportunity of oxidizing the sub-chloride as fast as it is formed. The oxidized image is always more difficult to tone than one which is unoxidized, hence the advantage of printing in a good light if possible. The writers believe that one of the principal causes of the variation in tone of silver prints, which is only too often to be seen, is caused by this difference in length of exposure to the light.

The operator must now be supposed to be cognizant of the operations of toning and fixing which are to be described in subsequent chapters, and that he has the finished trial print of the particular landscape negative before him. He sees whether the middle distance or far distance is obtrusive, and notes which portions require to be softened down by tissue paper, or to be brought nearer by strengthening the high-lights, and eventually forms a picture of it as it should be, centring his imagination in it as built up round the point of principal interest. He endeavours to see whether the sweeps of light and shade lead up to this principal object in the view, and whether, if light, it is in contrast with an immediate dark part of the picture, or vice versa.

Knowing that this is one of the laws of art, he next should endeavour practically to give effect to his imaginative picture by the judicious manipulation of tissue paper, the crayon, and the paint, such as described in Chapter IX. The next point to attend to is as to whether the picture requires clouds or not, and if he have a stock of cloud negatives of the right size, he must endeavour to pick out one, a portion of which will compose well with the lines of the picture,[21] and at the same time be correct as regards light and shade. When such a negative is selected, it remains to print it in. A white sky is an abomination, and a plain tinted one without gradation is nearly as bad. If, therefore, the operator has the heart and means to do this double printing, he should never neglect to do it.

But we would here remind him that when a sky-negative has been used with a particular view, it should always be devoted to that landscape. Nothing could be in worse taste, or further from nature, than to use the same sky with different landscapes. We once saw a frame of sixteen views, thirteen of which were backed with the same sky; this was bad enough, but the absurdity went further, and in the same exhibition were landscapes by another photographer with the same sky! The inference is that both these photographers bought their sky negatives, printed them, and exhibited them as their own—a proceeding to which a harsh name might be given. To use a cloud negative properly, the reader should consult the chapter on "Combination Printing."

There is another artifice, however, that does away with the blank sky. It is practised by some of the leading photographers in England, and may be put in requisition instead of the more elaborate double printing. In order to do this, a not quite opaque sky—that is, one which "prints in" a little—is necessary. Very effective clouds may be produced by a paint-brush and lamp-black, Indian ink, or gamboge, by painting them artistically at the back of the negative. It matters not if the clouds so formed show sharp lines and dots, since, if the printing be done in diffused light, the thickness of the glass plate on which the negative is taken shades these off, and gives them the soft edges which are natural to clouds. The clouds may take any of the usual shapes as seen in nature, and the paint should not be applied too strongly, but should have a certain amount of transparency. In some negatives we have seen taken on dry plates, the sky was very transparent, and, when printed in the ordinary manner, showed a good deal more than perceptible tint. Yet, by a judicious masking, fleecy clouds floating in a light sky were produced, which deceived the greatest connoisseurs in such matters.

We will now describe how such a negative should be prepared for printing.

Black varnish should be carefully run round the sky-line on the face of the negative, for about a quarter of an inch. On the back of the negative the medium should cover the sky to within one-eighth of an inch of the sky-line, and by this means a sharp but slightly softened edge of the distant landscape was projected. The breadth of the black varnish border on the back was slightly greater than that on the film side of the negative, being about an inch. A piece of cardboard was also roughly cut out to the sky-line, and left sufficiently broad so as to more than cover the sky when laid flat on it. The negative with the clouds painted on it was now placed in the pressure-frame, with the sensitive paper in contact with it. Outside the frame, and corresponding with the sky-line, the edge of the cardboard was placed, a small bar to act as a weight was placed across it as shown in the figure, and the top end supported by a couple of wooden pegs. The printing took place in diffused light. When the picture was withdrawn from the frame, the sky, being shaded gradually by the card, was printed in lightly, whilst the remaining portion of the negative received the full light; the sky, as is right it should be, was darker near the zenith than toward the horizon, where it was, in fact, white; but since the clouds were printed in at the top, the baldness of the white sky was avoided.