On ethylidenamine silver sulphate

Abstract

ALDEHYDE AMMONIA precipitates metallic silver from many of its salts almost as readily as from the nitrate. A mixture of solutions of silvet' sulphate and aldehyde ammonia produces a mirror when warmed, and at common temperatures evaporates to dryness, with but slight decomposition. The fact that a sulphate solution decomposed less readily than the nitrate led to the hope that an investigation of the sulphate compound would throw more light on the constitution of silver amines. The first experiments were made with ammoniacal aqueous solutior.s of silver sulphate and aldehyde ammonia. Analyses proved the crystalline product to be a mixture. Alcoholic ammonia was next used as a solvent, and the analysis of the first crop of crystals showed nearly pure Ag2S04(NH~)4' 0'6 per cent of carbon was found and a solution of the crystals reacted for aldehyde. Aqueous solutions of silver sulphate and a lal'ge excess of aldehyde ammonia, over four molecules of the latter to olle of the former, yielded either mixtures or ammonio silver sulphate. When, however, aldehyde ammonia is dissolved in a small quantity of water, and silver sulphate, in the proportion of one molecule of the lat.ter to four molecules of the formel', is slowly added with constant agitation; and after some hours the small black residue filtered off and the solution left to spontaneous evaporation, few or no crystals of the ammonio, sulphate form, but colo1'less tl'ansparent crystals separate, whICh react strongly for aldehyde. At summer temperatures tabulat' crystals, and at from 10° to 15° C. elongated crystals, predominate. The following analyses were made of carefully selected and well-defined tabular crystals, which were from 2 to 5mm in diameter, and which were freed as much as possible from the mother liquor by blotting paper, then washed with alcohol and finally with ether. They were considel'ed dry when they did not lose weight on the balance in five or ten minutes.