a New Class of Salts. 217 



ammonia dissolves nitroprusside of silver, but it soon deposits 

 white crystals, which are apt to be contaminated by oxide of 

 iron. These white shining crystals are a compound of the salt 

 with ammonia, and are quickly decomposed, even by water 

 alone, but very readily by water acidulated with nitric acid. 

 Ammonia is now found in solution and nitroprusside of silver 

 remains. If ammonia and nitroprusside of silver be boiled 

 together, total decomposition takes place. 



The salt was decomposed by sulphuric acid, the silver esti- 

 mated as a chloride and the iron as peroxide. Each salt ana- 

 lysed was prepared at different times. 



1. H'TSS grs. gave 2*749 grs. oxide of iron and 9*925 grs. 



chloride of silver. 

 II. 22*838 grs. gave 4-220 Fe^O^ and 15*18 AgCl. 



III. 16*675 grs. gave 3*115 Fe^O^ and 11*09 AgCl. 



IV. 26*545 grs. gave 4*970 Fe^O^ and 17*78 AgCl. 



The combustions were made in the usual way. 



I. 8 '350 grs. gave 0*252 gr. water and 4*045 grs. carbonic 



acid. 

 II. 8*385 grs. gave 0*234 HO and 4*150 CO^. 



III. 7*900 grs. gave 0*183 HO and 3*820 CO^. 



IV. 9*415 grs. gave 0*120 HO and 4*577 CO^. 



As this salt was well calculated to give correct knowledge 

 with regard to the composition of the nitroprussides generally, 

 the nitrogen was carefully determined by the three best pro- 

 cesses, viz. those of Dumas, Liebig and Bunsen. 



I. Quantitative estimation of nitrogen : — 



6*808 grs. salt gave 69 C.C. nitrogen gas, 



the thermometer being 7°*7 C and the barometer 30*094 

 inches. This makes the nitrogen 19*299 per cent. 



II. Liebig's method : — 

 Tubes. Vol. mixed gases. Vol. after absorption. Vol. of carbonic acid. 



123*05 46-70 76*35 



Hence the proportion of nitrogen to carbonic acid is as 

 1 : 163. This, calculated on 13*288, the mean quantity of 

 carbon, gives 1902 per cent. 



