A NEVy CLASS OF SALTS. 
495 
With a quantity of hydrogen so small as that in the above analysis, it is difficult to 
obtain accordant results in an organic analysis. A portion of well-dried salt was 
therefore heated in an F tube, to which a tube filled with chloride of calcium was 
attached. 
5*375 grs. gave 0*085 gr. water, equal to 0*175 H. per cent. 
4*000 grs. gave 0*065 gr. water, equal to 0*180 H. per cent. 
It is therefore quite certain that the silver salt dried at 212° still retains 1^ per 
cent, of water. It loses however this water at a higher heat and becomes anhydrous. 
The formula of the silver salt is therefore Feg Cyi 2 3NO, Ag 5 -l- 2 HO. 
Nitroprusside of Copper. 
15. This salt is obtained by adding a solution of a copper salt to that of a nitro- 
prusside. As it is insoluble in cold water, and almost entirely so in hot, it may be 
washed to any extent. 
It is of a pale green colour, which changes to slate colour when exposed to light 
in the moist state. It is quite insoluble in alcohol. It is decomposed by the caustic 
alkalies, first passing into a dark brown basic nitroprusside, and then into oxide of 
copper and a soluble nitroprusside. 
Nitroprusside of copper, dried in the hot chamber at about 100°Fahr., still lost 
weight in the water-bath. 
45*60 grs. lost in water-bath 4*525, or 9*922 per cent. 
25* 1 2 grs. lost in water-bath 2*870, or 11*425 per cent. 
The analysis of the dried salt was made by decomposing it with sulphuric acid, 
and estimating the two metals as oxides, after separating them in the usual way by 
sulphuretted hydrogen. 
I. 22*24 grs. gave 6*325 grs. oxide of copper and 6*515 grs. peroxide of iron. 
II. 2 TOO grs. gave 6*018 grs. oxide of copper and 6* 120 grs. peroxide of iron. 
The combustions were made with chromate of lead and with oxide of copper. 
I. 8*100 grs. gave 0*230 gr. water and 6*343 grs. carbonic acid. 
II. 7'977 gi’s. gave 0*240 gr. water and 6*217 gi’S- carbonic acid. 
III. 9*887 gi'S. gave 0*330 gr. water and 7‘694 grs. carbonic acid. 
IV. 1 1*507 grs. gave 0*320 gr. water and 8*936 grs. carbonic acid. 
The nitrogen was determined in three different ways. 
I. Dumas’ quantitative method : — 
6*226 grs. gave 98 CC. nitrogen gas. Barom. 30*105 inches. Therm. 8°*8 C. 
II. Bunsen’s method ; — 
Vol. 
Vol. mixed gases (moist) . 246*3 
Vol. after absorption (dry) . 121*1 
Barom. 
Therm. 
Col. mere, 
inche.s. 
0 
29*988 
15*6 
219*7 
30*069 
15*4 
348*0 
3 s 2 
