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Silver Albuminate

solution, ammonia, nitrate and adding

SILVER ALBUMINATE (Pr., Albuminate d'argent ; Ger., Silberalbuminat) A very ill-defined compound of silver nitrate and albumen, which was supposed to form one of the sensitive compounds in the old sensitised albumen paper.

SILVER (Fr., Am monio-nitrate d'argent ; Ger., Salpeter saures Silberoxydammoniah, or Silber oxydammonialt) Synonym, ammonio-oxide of silver. Molecular weight, 204. Solubilities, very soluble in water and alcohol. It takes the form of colourless needles, and is obtained by mixing a solution of ammonia with a silver nitrate solution and carefully evapora ting, but nearly always it is prepared in solu tion by adding ammonia to silver nitrate solution till a clear solution is obtained ; at first, on the addition of the ammonia, a blackish brown pre cipitate of silver oxide is formed, which dissolves in excess of ammonia to form a clear solution. A solution thus prepared is used for sensitising plain paper, and also to form silver bromide in emulsion making. According to the above formula, two molecules of ammonia are required for every molecule of silver nitrate, but it is possible to obtain a clear solution with only half the quantity of ammonia by dividing the silver solution into two equal parts, to the one adding enough ammonia solution to obtain a clear solution, and then adding the other half of the silver nitrate. The solution containing

the lesser quantity of ammonia gives emulsions freer from fog, but usually of lower sensitiveness.

SILVER (Fr., Am monio-carbonate d'argent ; Ger., Kohlen saures Silberoxydammoniah) (ascribed to it by Eder). Mole cular weight, 229. Solubilities, soluble in water and alcohol. It is not found in the solid form, but always in solution, and is prepared by adding a solution of ammonium carbonate to a silver nitrate solution, when a yellow precipitate of silver carbonate is first formed, which dissolves in excess of the ammonium carbonate, carbonic acid being evolved. It is occasionally used in emulsion making, particularly for slow, clean working emulsions.

SILVER (Pr., Am monio - citrate d'argent ; Ger., Citronen saures Silberoxydammoniah) Solubilities, very soluble in water and alcohol. It is prepared by adding citric acid to silver nitrate solution, and then a solution of ammonia ; a white, curdy precipitate of silver citrate first forms which is soluble in excess of ammonia. It is used in preparing slow, clean-working negative and positive emulsions, and also for printing out emulsions.