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Russell's Tannin Process, Modified

Cleaning the Plate.

In order to clean the plates, make a stock solution of 2 oz. of bichromate of potash, 2 oz. of sulphuric acid, and 1 qt. of water (a green quart wine-bottle may be used). Pour the solution into a shallow tray; soak in it the plates to be cleansed, and afterwards wash the plates in water and dry them; then pour on each plate a small quantity of old collodion; rub it all over the plate with a tuft of cotton, and then clean it off with a dry linen cloth. It will perfect the cleaning if the plate be dipped in pure water and again dried with a clean linen cloth. The bichromate of potash solution may be filtered back into the bottle for future use.

To Coat the Plate. 1. Cover the plate with a bromised collodion.

Take care, in all cases, gently to oscillate on running off the excess of collodion, or white marks, visible in a subsequent stage of the process, will be formed. 2. When the film is somewhat fixed, put the plate, by the aid of a dipper. in a well-bath of a 50 gr. nitrate of silver solution, and let it remain in the solution 10 minutes.

3. Put the plate in a well-bath of distilled water until what are called the " greasy " marks disappear. 4. Put the plate in a well-bath of a 10 gr. solution of bromide of ammonium, or cadmium, or magnesium, or of potassium. It may be best to adopt that bromide which enters into the preparation of the collodion. Let the plate remain in this solution about 1 minute. Occasionally filter this bath solution, in order to remove the excess of bromide of silver which is deposited in the bath. Keep a stock bottle of this bromide solution to supply the waste drippings. 5. Put the plate for a short time in a well-bath of distilled water. 6. Wipe the back of the plate, and let it drain for a short time, and then place it in a well-bath of 10 or 15 grs. of tannin to the oz. of distilled water; let the plate remain in this solution 4 or 5 minutes, and then, on removing it from this bath, let it rest on one end, to dry. When dry, it is ready for the camera, and it will keep a long time.

It should be rapidly and evenly dried, and a stone bottle of hot water may be so used as to hasten the drying. Tannin which dissolves most easily in water, is to be preferred. Add to the tanninbath 3 or 4 drops of creosote, and it will keep clear. A little experience will show how long a time the plate must be exposed to light in the camera. It will be best, in the beginning, not to make a very short exposure; harsh pictures are the result of long exposures, and soft pictures will bear a considerable amount of exposure in the camera without being fogged-even for 10 minutes.

Developing. 1. The film sometimes appears to be in a rotten state, and to crack up when water is poured on it.

This will not happen if a small quantity of alcohol be added to the water solution first poured over it. 2. Take a solution of 2 grs. to the oz. of water of carbonate of ammonia; add to it some alcohol, and flush the plate with it; pour this off into a glass, and add to it from gr. to 1 gr. of pyrogallic acid, in solution, and pour it back again on the plate. This picture will instantly appear, and the details may be allowed to come out well. The image will not be dark. 3. Pour off the alkaline pyro-solution, and gently wash the plate; add a few drops of citric acid (1 or two grs. of citric acid to the oz. of distilled water); pour it over the plate, and run off; or pour an acid pyro-solution over the plate instead of acid solution alone. Again gently pour distilled water on the plate, and run it off.

4. It will be found to be convenient to dissolve 1 dr. of pyrogallic acid in 1 oz. of alcohol, and to add to this 1 oz. of distilled water. Use 1 dr. graduate, and 16 minims of this solution will give 1 gr. of pyrogallic acid; also have a 2 oz. bottle of distilled water and dissolve in it 2 drs. of citrio acid; 8 minims of this will be 1 gr. of citric acid. Have also an oz. bottle of a 10 gr. solution of nitrate of silver; and lastly, have at hand a pint bottle of distilled water, 1 or 2 glass oz. graduabout a fluidounce. ates, and 3 or 4 developing-glasses, which hold 5. The development of a plate is completed by solutions of gr. to 1 gr. of pyrogallic acid, and 1 gr. or more of citric acid to the oz. of water, and the addition of 1 drop to 3, 4, or more of the 10 gr. nitrate of silver solution. If the picture is strongly out when the ammonia is washed off, let it be dosed with an excess of acid silver; if feeble, let an excess of pyrogallic acid be used. If there be a sign of fogging when pushing the development with an excess of nitrate of silver, immediately pour off the developer, gently wash the plate and flush it with the 8 gr. bromide solution. The image, as it at first shows its strength or weakness, very soon teaches the manner in which the plate is to be dealt with.

Lastly. Gently wash the plate, fix the image with a strong solution of hyposulphite of soda, distilled or common water, and dry it. and, when the picture is "cleared," wash it with The three steps which have made the tannin process of Major Russell simple, clean, and certain, are: First, the use of the bromide bath; second, the use of the tannin bath, and third, the use of the acid solution, either alone or mixed with pyrogallic acid, after the alkaline solution of carbonate of ammonia has been washed off, not forgetting the mixture of some alcohol with the first application of water to the film on the development. -