Part 98

In reclaiming old gold solutions, all liquids containing gold, with the exception of baths of which cyanide forms a part, must be strongly acidulated with chlorhydric or sulphuric acid, if they are not already acid in their nature. They are afterwards diluted with a large proportion of ordinary water, and a solution of sulphate of ferroprotoxide (green vitriol) is poured in in excess. It is recognized that the filtered liquid no longer contains gold when the addition of a new quantity of ferric sulphate does not occasion any cloudiness. Gold precipitated in the form of a reddish or blackish powder is collected on a filter and dried in an oven with weights equal to its own of borax, saltpeter, and carbonate of potash. The mass is afterwards introduced gradually into a fireproof crucible and carried to a white-red heat in a furnace. When all the matter has been introduced, a stronger blast is given by closing the furnace, so that all the metal collects at the bottom of the crucible. On cooling, a gold ingot, chemically pure, will be obtained. This mode of reduction is also suitable for impure chloride of gold, and for the removal of gilding, but not for solutions containing cyanides, which never give up all the gold they contain; the best means of treating the latter consists in evaporating them to dryness in a cast-iron boiler, and in calcining the residue in an earthen crucible at the white red. A small quantity of borax or saltpeter may be added for facilitating the fusion, but it is not generally necessary. The gold separated collects at the bottom of the crucible. It is red, if saltpeter is employed; and green, if it is borax.

To reclaim silver place the old films, plates, paper, etc., in a porcelain dish, so arranged that they will burn readily. To facilitate combustion, a little kerosene or denatured alcohol poured over the contents will be found serviceable.

Before blowing off the burnt paper, place the residue in an agateware dish, the bottom of which is covered with a solution of saltpeter and water. Place the whole on the fire, and heat it until the silver is separated as a nitrate.

The solution being complete, add to the mass a little water and hydrochloric acid, when in a short time the serviceable silver chloride will be obtained. If the films should not give up their silver as freely as the plates, then add a little more hydrochloric acid or work them up separately. Silver reclaimed in this way is eminently suitable for silver-plating all sorts of objects.

«FIXING AND CLEARING BATHS:»

«The Acid Fixing and Clearing Bath.»—Add 2 ounces of S. P. C. clarifier (acid bisulphite of sodium) solution to 1 quart of hypo solution 1 in 5.

«Combined Alum and Hypo Bath.»—Add saturated solution of sulphite of sodium to saturated solution of alum till the white precipitate formed remains undissolved, and when the odor of sulphurous acid becomes perceptible.

Mix this solution with an equal bulk of freshly prepared hypo solution 1 in 5, and filter.

This bath will remain clear.

«Clearing Solution» (Edward’s).—

Alum 1 ounce avoirdupois Citric acid 1 ounce avoirdupois Sulphate of iron, crystals 3 ounces avoirdupois Water 1 imperial pint

This should be freshly mixed.

«Clearing Solution.»—

Saturated solution of alum 20 ounces Hydrochloric acid 1 ounce

Immerse negative after fixing and washing. Wash well after removal.

«Reducer for Gelatin Dry-Plate Negatives.»—

I.—Saturated solution of ferricyanide of potassium 1 part Hyposulphite of sodium solution (1 in 10) 10 parts

II.—Perchloride of iron 30 grains Citric acid 60 grains Water 1 pint

«Belitski’s Acid Ferric-Oxalate Reducer for Gelatin Plates.»—

Water 7 ounces Potassium ferric oxalate 2 1⁠/⁠2 drachms Crystallized neutral sulphite of sodium 2 drachms Powdered oxalic acid, from 30 to 45 grains Hyposulphite of soda 1 1⁠/⁠2 ounces

The solution must be made in this order, filtered, and be kept in tightly closed bottles; and as under the influence of light the ferric salt is reduced to {536} ferrous, the preparation must be kept in subdued light, in non-actinic glass bottles.

«Orthochromatic Dry Plates—Erythrosine Bath (Mallman and Scolik).»—Preliminary bath:

Water 200 cubic centimeters Stronger ammonia 2 cubic centimeters

Soak a plate for 2 minutes.

Color bath:

Erythrosine solution (1 in 1,000) 25 cubic centimeters Stronger ammonia (0.900) 4 cubic centimeters Water 175 cubic centimeters

The plate should not remain longer in the bath than 1 1⁠/⁠4 minutes.

«PAPER-SENSITIZING PROCESSES:»

«Blueprint Paper.»—I.—The ordinary blue photographic print in which white lines appear on a blue ground may be made on paper prepared as follows:

A.—Potassium ferricyanide 10 drachms Distilled water 4 ounces

B.—Iron ammonia citrate 15 drachms Distilled water 4 ounces

Mix when wanted for use, filter, and apply to the surface of the paper.

With this mixture no developer is required. The paper after exposure is simply washed in water to remove the unaltered iron salts. The print is improved by immersion in dilute hydrochloric acid, after which it must be again well washed in water.

II.—The following process, credited to Captain Abney, yields a photographic paper giving blue lines on a white ground:

Common salt 3 ounces Ferric chloride 8 ounces Tartaric acid 3 1⁠/⁠4 ounces Acacia 25 ounces Water 100 ounces

Dissolve the acacia in half the water and dissolve the other ingredients in the other half; then mix.

The liquid is applied with a brush to strongly sized and well rolled paper in a subdued light. The coating should be as even as possible. The paper should be dried rapidly to prevent the solution sinking into its pores. When dry, the paper is ready for exposure.

In sunlight, 1 or 2 minutes is generally sufficient to give an image; while in a dull light as much as an hour is necessary.

To develop the print, it is floated immediately after leaving the printing frame upon a saturated solution of potassium ferrocyanide. None of the developing solution should be allowed to reach the back. The development is usually complete in less than a minute. The paper may be lifted off the solution when the face is wetted, the development proceeding with that which adheres to the print.

When the development is complete, the print is floated on clean water, and after 2 or 3 minutes is placed in a bath, made as follows:

Sulphuric acid 3 ounces Hydrochloric acid 8 ounces Water 100 ounces

In about 10 minutes the acid will have removed all iron salts not turned into the blue compound. It is next thoroughly washed and dried. Blue spots may be removed by a 4 per cent solution of caustic potash.

The back of the tracing must be placed in contact with the sensitive surface.

III.—Dissolve 3 3⁠/⁠4 ounces of ammonia citrate of iron in 18 ounces of water, and put in a bottle. Then dissolve 2 5⁠/⁠8 ounces of red prussiate of potash in 18 ounces of water, and put in another bottle. When ready to prepare the paper, have the sheets piled one on top of the other, coating but one at a time. Darken the room, and light a ruby lamp. Now, mix thoroughly equal parts of both solutions and apply the mixture with a sponge in long parallel sweeps, keeping the application as even as possible. Hang the paper in the dark room to dry and keep it dark until used. Any of the mixture left from sensitizing the paper should be thrown away, as it deteriorates rapidly.

Often, in making blueprints by sunlight, the exposure is too long, and when the frame is opened the white lines of the print are faint or obscure. Usually these prints are relegated to the waste basket; but if, after being washed as usual, they are sponged with a weak solution of chloride of iron, their reclamation is almost certain. When the lines reappear, the print should be thoroughly rinsed in clear water.

Often a drawing, from which prints have already been made, requires changing. The blueprints then on hand are worthless, requiring more time to correct {537} than it would take to make a new print. An economical way of using the worthless prints is to cancel the drawing already thereon, sensitize the reverse side, and use the paper again.

«How to Make Picture Postal Cards and Photographic Letter Heads.»—I.—Well-sized paper is employed. If the sizing should be insufficient, resizing can be done with a 10 per cent gelatin solution, with a 2 per cent arrowroot paste, or with a 50 per cent decoction of carrageen. This size is applied on the crude paper with a brush and allowed to dry. The well-sized or resized papers are superior and the picture becomes stronger on them than on insufficiently sized paper. Coat this paper uniformly with a solution of 154 grains of ferric oxalate in 3 1⁠/⁠2 fluidounces of distilled water, using a brush, and allow to dry. Next, apply the solution of 15 1⁠/⁠2 grains of silver nitrate in 3 1⁠/⁠2 fluidounces of water with a second brush, and dry again. Coating and drying must be conducted with ruby light or in the dark.

The finished paper keeps several days. Print deep so as to obtain a strong picture and develop in the following bath:

Distilled water 3 1⁠/⁠2 fluidounces Potassium oxalate (neutral) 340 grains Oxalic acid 4 grains

After developing the well-washed prints, fix them preferably in the following bath:

Distilled water 3 1⁠/⁠2 fluidounces Sodium thiosulphate 75 grains Gold chloride solution (1 in 100) 80 minims

Any other good bath may be employed.

II.—Starch is dissolved in water and the solution is boiled until it forms a thin paste. Carmine powder is added, and the mixture is rapidly and assiduously stirred until it is homogeneous throughout. It is now poured through muslin and spread by means of a suitable pencil on the paper to be sensitized. Let dry, then float it, prepared side down on a solution of potassium chromate, 30 parts in 520 parts of distilled water, being careful to prevent any of the liquid from getting on the back or reverse side. Dry in the dark room, and preserve in darkness. When desired for use lay the negative on the face of the paper, and expose to the full sunlight for 5 or 6 minutes (or about an hour in diffused light). Washing in plenty of water completes the process.

«A Simple Emulsion for Mat or Printing-Out Paper.»—One of the very best surfaces to work upon for coloring in water color is the carbon print. Apart from its absolute permanency as a base, the surface possesses the right tooth for the adhering of the pigment. It is just such a surface as this that is required upon other prints than carbon, both for finished mat surfaces and for the purposes of coloring. The way to obtain this surface upon almost any kind of paper, and to print it out so that the correct depth is ascertained on sight, will be described. Some of the crayon drawing papers can be utilized, as well as many other plain photographic papers that may meet the desires of the photographer. If a glossy paper is desired, the emulsion should be coated on a baryta-coated stock.

There will be required, in the first place, 2 half-gallon stoneware crocks with lids. The best shape to employ is a crock with the sides running straight, with no depressed ridge at the top. One of these crocks is for the preparation of the emulsion, the other to receive the emulsion when filtered. An enameled iron saucepan of about 2 gallons capacity will be required in which to stand the crock for preparing the emulsion, and also to remelt the emulsion after it has become set. The following is the formula for the emulsion, which must be prepared and mixed in the order given. Failure will be impossible if these details are scrupulously attended to.

Having procured 2 half-gallon stoneware crocks with lids, clean them out well with hot and cold water, and place into one of these the following:

Distilled water 10 ounces Gelatin (Heinrich’s, hard) 4 ounces

Cut the gelatin into shreds with a clean pair of scissors. Press these shreds beneath the water with a clean strip of glass and allow to soak for 1 hour. Now proceed to melt the water-soaked gelatin by placing the crock into hot water in the enameled saucepan, the water standing about half way up on the outside of the crock. Bring the water to boiling point, and keep the gelatin occasionally stirred until it is completely dissolved. Then remove the crock to allow the contents to cool down to 120° F. Now prepare the following, which can be done while the gelatin is melting: {538}

No. 1

Rochelle salts 90 grains Distilled water 1 ounce

No. 2

Chloride of ammonia 45 grains Distilled water 1 ounce

No. 3

Nitrate of silver, 1 ounce and 75 grains Citric acid (crushed crystals) 95 grains Distilled water 10 ounces

No. 4

Powdered white alum 90 grains Distilled water (hot) 5 ounces

The latter solution may be made with boiling water. When these solutions are prepared, pour into the hot gelatin solution No. 1, stirring all the while with a clean glass rod. Then add No. 2. Rinse the vessel with a little distilled water, and add to the gelatin. Now, while stirring gradually, add No. 3, and lastly add No. 4, which may be very hot. This will cause a decided change in the color of the emulsion. Lastly add 2 ounces of pure alcohol (photographic). This must be added very gradually with vigorous stirring, because if added too quickly it will coagulate the gelatin and form insoluble lumps. The emulsion must, of course, be mixed under a light not stronger than an ordinary small gas-jet, or under a yellow light obtained by covering the windows with yellow paper. The cover may now be placed upon the crock, and the emulsion put aside for 2 or 3 days to ripen.

At the end of this time the contents of the crock, now formed into a stiff emulsion, may be remelted in hot water by placing the crock in the enameled saucepan over a gas stove. The emulsion may be broken up by cutting it with a clean bone or hard-rubber paper cutter to facilitate the melting. Stir the mixture occasionally until thoroughly dissolved, and add the following as soon as the emulsion has reached a temperature of about 150° F.:

Distilled water 4 ounces Pure alcohol 1 ounce

The emulsion must now be filtered into the second crock. The filtering is best accomplished in the following manner: Take an ordinary plain-top kerosene lamp chimney, tie over the small end two thicknesses of washed cheese cloth. Invert the chimney and insert a tuft of absorbent cotton about the size of an ordinary egg. Press it carefully down upon the cheese cloth. Fix the chimney in the ring of a retort stand (or cut a hole about 3 inches in diameter in a wooden shelf), so that the crock may stand conveniently beneath. In the chimney place a strip of glass, resting upon the cotton, to prevent the cotton from lifting. Now pour in the hot emulsion and allow the whole of it to filter through the absorbent cotton. This accomplished, we are now ready for coating the paper, which is best done in the following manner:

Cut the paper into strips or sheets, say 12 inches wide and the full length of the sheet. This will be, let us suppose, 12 x 26 inches. Attach, by means of the well-known photographic clips, a strip of wood at each end of the paper upon the back. Three clips at each end will be required. Having a number of sheets thus prepared, the emulsion should be poured into a porcelain pan or tray, kept hot by standing within another tray containing hot water. The emulsion tray being, say, 11 x 14 size, the paper now is easily coated by holding the clipped ends in each hand, then holding the left end of the paper up, and the right-hand end lowered so that the curve of the paper just touches the emulsion. Then raise the right hand, at the same time lowering the left hand at the same rate. Then lower the right hand, lifting the left. Repeat this operation once more; then drain the excess of emulsion at one corner of the tray, say, the left-hand corner. Just as soon as the emulsion has drained, the coated sheet of paper may be hung up to dry, by the hooks attached to the clips, upon a piece of copper wire stretched from side to side of a spare closet or room that can be kept darkened until the paper is dry. In this way coat as much paper as may be required. When it is dry it may be rolled up tight or kept flat under pressure until needed.

If any emulsion remains it may be kept in a cool place for 2 weeks, and still be good for coating. Be sure to clean out all the vessels used before the emulsion sets, otherwise this will present a difficult task, since the emulsion sets into an almost insoluble condition.

This emulsion is so made that it does not require to be washed. If it is washed it will become spoiled. It is easy to make and easy to use. If it is desired that only small sheets of paper are to be coated, they may be floated on the emulsion, but in this case the paper must be damp, which is easily accomplished by {539} wetting a sheet of blotting paper, then covering this with two dry sheets of blotting paper. Place the sheets to be coated upon these, and place under pressure during the night. Next day they will be in good condition for floating.

When the coated paper is dry it may be printed and toned just the same as any other printing-out paper, with any toning bath, and fixed in hyposulphite of soda as usual. Toning may be carried to a rich blue black, or if not carried too far will remain a beautiful sepia color. After well washing and drying, it will be observed that the surface corresponds with that of a carbon print; if the paper has been of a somewhat absorbent character, the surface will be entirely mat, and will give an excellent tooth for coloring or finishing in sepia, black and white, etc.

«How to Sensitize Photographic Printing Papers.»—I.—The older form of paper is one in which the chemicals are held by albumen. Silver is said to combine with this, forming an albuminate. Pictures printed on this would be too sharp in their contrasts, and consequently “hard”; this is avoided by introducing silver chloride.

To prepare this form of paper, beat 15 ounces of fresh egg albumen with 5 ounces of distilled water, dissolve in it 300 grains of ammonium chloride, set aside for a time, and decant or filter. Suitable paper is coated with this solution by floating, and then dried. The paper is “sensitized” by floating it on a solution of silver nitrate in distilled water, about 80 grains to the ounce, with a drop of acetic acid. The paper is dried as before, and is then ready for printing. The sensitizing must, of course, be done in the dark room.

The reaction between the ammonium chloride present in the albumen coating produces a certain quantity of silver chloride, the purpose of which is shown above. Of course, variations in the proportions of this ingredient will give different degrees of softness to the picture.

II.—The bromide and chloride papers which are now popular consist of the ordinary photographic paper sensitized by means of a thin coating of bromide or chloride emulsion. In “Photographic Printing Methods,” by the Rev. W. H. Burbank, the following method is given for bromide paper:

A.—Gelatin (soft) 42 1⁠/⁠2 grains Bromide of potassium 26 grains Distilled water 1 ounce

B.—Nitrate of silver 33 1⁠/⁠3 grains Distilled water 1 ounce

Dissolve the bromide first, then add the gelatin and dissolve by gentle heat (95° to 100° F.). Bring the silver solution to the same temperature, and add in a small stream to the gelatin solution, stirring vigorously, of course in non-actinic light. Keep the mixed emulsion at a temperature of 105° F. for half an hour, or according to the degree of sensitiveness required, previously adding 1 drop of nitric acid to every 5 ounces of the emulsion. Allow it to set, squeeze through working canvas, and wash 2 hours in running water. In his own practice he manages the washing easily enough by breaking the emulsion up into an earthen jar filled with cold water, and placed in the dark room sink. A tall lamp chimney standing in the jar immediately under the tap conducts fresh water to the bottom of the jar, and keeps the finely divided emulsion in constant motion; a piece of muslin, laid over the top of the jar to prevent any of the emulsion running out, completes this simple, inexpensive, but efficient washing apparatus.

Next melt the emulsion and add one-tenth of the whole volume of glycerine and alcohol; the first to prevent troublesome cockling of the paper as it dries, the second to prevent air bubbles and hasten drying. Then filter.

With the emulsion the paper may be coated just as it comes from the stock dealer, plain, or, better still, given a substratum of insoluble gelatin, made as follows:

Gelatin 1 3⁠/⁠5 grains Water 1 ounce

Dissolve and filter; then add 11 drops of a 1 in 50 filtered chrome alum solution. The paper is to be floated for half a minute on this solution, avoiding air bubbles, and then hung up to dry in a room free from dust. The purpose of this substratum is to secure additional brilliancy in the finished prints by keeping the emulsion isolated from the surface of the paper. The paper should now be cut to the size desired.

We do not know of these processes having been applied to postal cards, but unless there is some substance in the sizing of the card which would interfere, there is no reason why it should not be. Of course, however, a novice will not get the results by using it that an experienced hand would.

«Ferro-Prussiate Paper.»—The following aniline process of preparing sensitive paper is employed by the Prussian and Hessian railway administrations. The {540} ordinary paper on reels is used for the purpose, and sensitized as follows:

Two hundred and fifty parts, by weight, of powdered potassium bichromate are dissolved in water; the solution should be completely saturated; 10 parts of concentrated sulphuric acid, 10 parts of alcohol (962), and 30 parts of phosphoric acid, are added successively, and the whole stirred together. The solution is sponged over the paper. It is not necessary to have the room absolutely dark, or to work by a red light, still the light should be obscured. The drying of the paper, in the same place, takes about 10 minutes, after which the tracing to be reproduced and the paper are placed in a frame, as usual, and exposed to daylight. On a sunny day, an exposure of 35 seconds is enough; in cloudy weather, 60 to 70 seconds; on a very dark day, as much as 5 minutes.

After exposure, the paper is fixed by suspending it for 20 minutes upon a bar in a closed wooden box, on the bottom of which are laid some sheets of blotting paper, sprinkled with 40 drops of benzine and 20 of crude aniline oil. The vapors given off will develop the design. Several impressions may be taken at the same time.

For fixing, crude aniline oil is to be used (anilinum purum), not refined (purissimum), for the reason that the former alone contains the substances necessary for the operation. The reproduced design is placed in water for a few minutes, and hung up to dry.