sist in a combination of emulsion of bromide of silver and gelatine emulsion with pyroxyline. Four different methods may be employed.

cess.

The collodionized and sensitized plate is first washed and then coated with albumen, which, in place of iodide, contains only 2 to 4 parts of common salt to 100 parts of albumen. The plate is then dried by submitting it to a great heat, and is not sensitive. Instead of sensitizing it in a silver-bath it is simply washed in the dark with pure water, whereby the layer becomes again sensitive.

Photo-diaphanie, or Process of Transferring Photographs together with the Albumen layer on Glass, Porcelain, etc. Float the paper 2 minutes in a bath consisting of nitrate of silver 6 parts and water 30 parts, then dry and expose it under a negative until the picture is copied. Wash with water, and tone the picture in a solution of 1 part of chloride of gold, 30 parts of sodium acetate, and 1050 parts of water, and neutralized with carbonate of sodium. Let the solution stand for 24 hours. After it has been used acidulate it slightly with hydrochloric acid, and when it is to be employed again neutralize the acid with carbonate of sodium and add, if necessary, some neutralized chloride of gold.

After toning the diaphanie picture is placed in pure water. As soon as the albumen layer begins to detach itself from the paper place the picture in a fixing bath consisting of sodium hyposulphite 4 parts and water 20, which will detach the film entirely from the paper. The film remains in the bath about 10 minutes, whereby it becomes very elastic and, after washing thoroughly with water, fit for transferring. It is laid wet on the article to be decorated, which must be entirely free from grease. If the film should not adhere properly wash it with a mixture of radical vinegar of 32° 1 part and distilled water 6, which renders it again elastic. When properly fastened remove all traces of acid by washing.

Photo-emulsions. Improvements by

1. Prepare a gelatine emulsion with bromide of silver (or iodide or chloride of silver). Dry and dissolve the emulsion in 3 to 10 times its quantity of formic or acetic acid. This acidulated emulsion is used either by itself or compounded with pyroxyline.

2. Dissolve pyroxyline by itself in one of the above acids with an addition of alcohol, and mix the solution with equal parts by volume of the above acidulated emulsion.

3. Prepare an ordinary collodion emulsion, precipitate it with water, dry the precipitate, and dissolve it in one of the acids mentioned, and add gelatine either direct or in solution.

4. Dissolve gelatine and pyroxyline and add finely powdered bromide of silver (iodide or chloride of silver), or produce them in the solution. These new emulsions can be used either dry or wet.

Photo-printing without a Press. A carbon picture is prepared on a glass plate in the usual manner, and the picture surrounded by a wooden frame which exactly encloses the glass plate. Now pour on a moderately warm mixture consisting of gelatine 1 part, gumArabic and glycerine each 2, and possessing the consistency of the mixture used in ordinary printing. When solidification has taken place the frame or rim is carefully removed with a hammer, and the gelatine plate, which has united itself with the carbon picture, is cautiously turned over. With respect to the printing the blackening of the picture is performed with a glass roller and is best managed with an elastic runner, as practised by the ordinary printer. The printing-ink, which must be of good consistency, is dissolved in oil of turpentine or benzol. This solution without an addition of varnish is poured on the plate and distributed by the glass roller. A non-coagulated albuminized paper is now spread over the blackened picture with due precautions. The paper should not lie too long on the plate, otherwise the albumen layer is apt to dissolve and soil the

plate. Moistening the plate with water is not necessary, as the plate is moist enough for the printing of a dozen pictures. After continuous use it exhausts itself, but still it is hygroscopic enough to absorb moisture in a few hours to be ready again for printing. This method has the advantage that the print is obtained in relief; also that round or cylindrical objects, as hasks, vases, etc., can be printed.

Photographic Process with Phosphorescent Substances. The following process has recently been published by | Warnerke: Coat a glass plate or paper with a layer of phosphorescent sulphide, using albumen as agglutinant to protect the powder from atmospheric influence. By preparing the phosphorescent surface upon a collodionized glass plate, and drawing off the film, a flexible layer is obtained. The plate coated with calcium sulphide is dark as long as not subjected to the action of light, but on exposure in the ⚫ camera for about 1 minute, and brought into the dark room, the points struck by the light will appear luminous. By placing the luminous picture upon an emulsion plate for about 5 minutes, and then developing it, a complete negative, but reverse, will be obtained. An exposure of the phosphorescent plate for a few seconds suffices to obtain an image visible in the dark room; heating the plate increases the luminosity. The picture remains luminous sufficiently long to allow of several copies being successively taken upon emulsion plates. It is a remark able fact that the picture produced in the camera is not sharp, the cause of this being evidently that the focus of the system of lenses is not corrected for rays promoting phosphorescence (especially ultra-violet and violet rays). A phosphorescent plate after having become luminous remains so in the dark for several hours, the luminosity gradually disappearing after that time, but in a red or green light it is extinguished in a few minutes. By exposing a luminous plate to bright daylight under a red glass plate, or green aniline layer, for several minutes it loses the power of emitting light in the dark. When a phosphorescent plate is exposed under an ordinary negative

a luminous image is obtained which, on being brought in contact with an emulsion plate, allows of a sharp posi tive being taken. By exposing a phos phorescent plate to the light, then covering it with a negative and a colored plate, extinguishing luminosity, and again exposing it, a luminous positive image is obtained, because the points struck by the colored light lose the power of emitting light in the dark. With phosphorescent plates it is possible, according to Warnerke, to obtain photographs from the red end of the spectrum. The entire surface of the plate must first be exposed to the light. On being struck by the spectrum of the sun the less refrangible rays (on the red end) destroy the illuminating power, and leave only Fraunhofer's dark lines gleaming upon the plate. These can then be transferred to a gelatine or collodion plate. Lieutenant Darwin has made similar experiments, using Balmain's luminous paint. He exposed a phosphorescent plate to the sunlight 3 to 4 seconds, covered it with a negative and a red glass plate, and submitted the whole to the rays of the sun for 1 minutes, and, as soon as the plate was brought into the dark room, a luminous negative made its appearance. This, on being brought in contact with a dry plate for 30 seconds, and then developed, gave a negative picture.

This

Photographic Reproduction. new process is based on the property of perchloride of iron being reduced to protochloride by light. The latter salt is not changed by a solution of prussiate of potash, while the former is immediately colored blue. The copying paper is sensitized by immersion in a bath formed of 100 parts of water, and 10 of perchloride of iron, and 5 of oxalic acid. The drawing, on transparent paper, is placed on a dry sheet of the copying paper and exposed to the light under glass from 15 to 30 seconds in summer and 40 to 70 seconds in winter. After exposure the sheet is placed in a bath of prussiate of potash (15: 100), which immediately colors blue all the parts where the perchloride has remained intact, but does not affect the places where the salt has been reduced by light.

2 or 3 days. The silver bath must be neutral, but the collodion acid red.

Developer for Photographs of Children. Water 1000 parts, sulphate of iron 50 parts, acetic acid 10 parts, boracic acid 10 parts, purified honey 7 parts, and alcohol 30 parts.

Developer for Photographs of Adults. Water 1000 parts, iron 60, acetic acid 60, alcohol 30.

Rapid Collodion Process by Borlinetto. Rectified alcohol 96 parts, ether of 66° 144 parts, gun cotton 2 parts, ammonium iodide and cadmium iodide each 1.66 parts.

Neutral Silver Bath. Nitrate of silver 10 parts, distilled water 100 parts, and a few drops of a saturated alcoholic solution of cadmium iodide.

Developing Bath. Sulphate of iron, alcohol, nitric acid, and radical vinegar each 5 parts, and water 100 parts. Fixing Bath. Sodium hyposulphite 1 part, water 8 parts.

Regaining of Silver from Residues of Gelatine Emulsions. Heat the residues and add caustic potash to prevent gelatinizing. When the solution boils pour it into an earthen-ware pot and add concentrated solution of potassium cyanide till the cream color of the emulsion disappears and a turbid fluid is formed. Then take 2 large zinc-carbon elements charged with potassium bichromate and sulphuric acid, connect a copper plate with the zinc-pole of the battery, and a large piece of coke with the carbon-pole, and hang both into the solution of cyanide of silver. Pure silver will at once be precipitated upon the copper plate. Allow the battery to act for an entire week and, when the solution is exhausted, add fresh residues. When the layer of silver is thick enough it is broken from the copper plate. It is chemically pure silver. The expense is somewhat less than melting. For 65 parts of zinc dissolved in the battery 108 parts of silver should be obtained.

Removing the Negative Layer from the Glass Plate is easily accomplished by pouring the following mixture over the dry, unlacquered negative: Gelatine 60 parts, water 600 parts, alcohol 120 parts, glycerine 10 parts, radical vinegar 7.5 parts. The plate is then placed in a horizontal position and

dried in a room free from dust. When dry run a knife around the edges, draw the film from the glass, pass it through dull varnish, and hang it up for a few minutes to dry. These negatives have the advantage over the glass negatives that they can be retouched from the back, which makes the retouching less visible in the printing and can be more conveniently kept, requiring less space, and besides are indestructible and can be easily handled.

Reproduction of Photo-negatives. The sensitive compound used for coating the plates is prepared from dextrine 4 parts, ordinary white sugar 5 parts, bichromate of ammonium 2 parts, water 100 parts, glycerine 2 to 8 drops, according to the condition of the atmosphere. A new well-cleansed plate is coated with the sensitive chromium solution; and, after the superfluous liquid has been allowed to flow off at one of the corners, the plate is dried in the dark upon a lithographic stone or metal plate for 10 minutes in a temperature of 120° to 160° F. The film, being perfectly dry, while yet warm, is put under a negative and printed in the shade for 10 or 15 minutes. As soon as it comes out of the printing frame the plate is again slightly warmed, and a brush, dipped into the graphite, applied over the surface of the image which should be just slightly visible. The application of the powder is done in a shaded corner of an ordinary room illuminated by daylight. Do not press hard upon the film with the brush, but move it over the surface as gently as possible; nor will it do to hurry the operation.

In proportion as the film cools so the image appears. By carefully breathing, or, still better, blowing upon the film, the operator will be enabled to accelerate the process, and when the picture has attained sufficient vigor the superfluous graphite may be taken off with a clean brush. A normal collodion is now applied composed of alcohol 500 parts, ether 500, and pyroxyline 15 to 20. When this film has set and hardened the edges are cut round with a knife, and the plate put into a porcelain dish of cold water. In 3 minutes the picture will be free from the glass, and the film may be employed in this position, or reversed with a soft brush, and

taken out of the water adhering either to the same glass plate or to another. A gentle stream of water falling upon the film will remove any chromium salt still remaining on it, and will also press down the loose film uniformly upon the glass surface. Finally the plate is allowed to dry in a perpendicular position. Further treatment of the plate with varnish follows as a matter of course. The image upon the collodion film is very thin; but it need not be feared that it will tear while in the water.

Sensitive Collodion Emulsion. Immerse the plates coated with collodion emulsion for 1 to 2 minutes in a solution of 1 part of gelatine in 100 of water, and then dry them. The plates treated thus are very sensitive, and, if correctly exposed, give a vigorous negative.

Sensitive Photo-paper. Dissolve 2 parts of nitrate of silver in 30 parts of water, and add part of citric acid. After this is dissolved add ammonia until precipitation ceases. Then redissolve with nitric acid, and leave the solution so that a small proportion of the precipitated citrate of silver remains. Let that settle perfectly, and then add 10 drops of nitric acid to every 2500 parts of solution. Sheets of the ordinary albuminized paper may be sensitized by floating for 1 minutes. There is no trouble from bubbles. The paper is more sensitive in printing than the ordinary paper, and tones splendidly. The paper is fumed in the usual way with strong ammonia. Paper made in this way will be found just as white at the end of 5 days as when first prepared.

Simple and Quick Process of Preparing Pyrogallic Acid. Ten parts of dry gallic acid are placed in a bottle or wide tube together with 30 parts of glycerine, and heated on a sand-bath to 375° or 390° F. until development of carbonic acid ceases. The conversion of gallic acid into pyrogallic acid takes place in a short time. The brown, tenacious fluid is, after boiling, diluted with 1000 parts of water, whereby a solution is obtained containing in 20 parts about part of pyrogallic acid. Care must be had that the temperature does not rise above 390° F. during the process.

Sutton's New Developer. Dissolve 8 parts of sulphate of iron in 16 parts of water, and in another vessel 4 parts of sugar in 3 parts of water. When all are dissolved, mix the two solutions, boil and filter the mixture, and allow the salt to crystallize. This produces a more vigorous development than ordinary sulphate of iron.

Sutton's Weak Silver-bath for Albuminized Paper. Dissolve 10 parts of nitrate of silver in 100 parts of water, and add, with constant stirring, ammonia until the solution becomes clear and the turbidity at first shown has disappeared. Then add nitric acid, drop by drop, until blue litmus paper begins to redden.

Toning Bath with Calcium Chloride and Sodium Acetate by Parkinson. Mix in a suitable flask calcium chloride 3 parts, sodium acetate 8 parts, calcium carbonate 8 parts, distilled water 100 parts. Mix 5 parts of this solution with 1000 parts of water, and add part of chloride of gold. The bath, after standing for 5 to 6 hours, is ready for use, and may be kept for some time.

Transfer Paper with Collodio-chloride of Silver is prepared in the following manner: Coat a stout piece of paper with a solution of caoutchouc thick enough to prevent the collodion from penetrating and spotting the paper. When the coating is dry pour upon it collodio-chloride of silver containing 1.5 parts of nitrate of silver, 1 part of citric acid, and some glycerine. The picture prints splendidly upon the caoutchouc surface; it is toned, fixed and washed, and then laid in water until it can be mounted. The article upon which the photo-print is to be mounted is coated with a solution of gelatine containing some glycerine. When dry dip the gelatinized article in a vessel with clean water, and place the wet print, picture side down, upon it, taking care to avoid air bubbles. The mounted picture is then allowed to dry. When it is entirely dry the caoutchouc paper is brushed over with benzine, and withdrawn from the picture.

Various Practical Receipts. I. Collodion for Hot Weather. Ether 300 parts, alcohol 360 parts, bromide of cadmium and bromide of ammonium