218 Dr. Playfair on the NitroprussideSf 



Bunsen's method: — 



Obs. vol. Barom. Therm. Col. mere. 



inches. ^ 



Vol. of mixed gases (moist) 110-8 757-7 16-2 C. 217*0 



Vol. after absorption (dry) 46-2 761-9 16*2 218-0 



Corrected vol. of mixed gases . . . 66*801 



Corrected vol. of nitrogen .... 25-800 



Vol. of carbonic acid 41-001 



Hence the proportion of nitrogen to carbonic acid is as 

 1 : 1-589, which calculated on 13-288 carbon, gives 19*512 

 per cent. 



III. 

 13-076 

 49*925 



13-177 



0-250 

 19-512*1 



4-060 J 



100-000 



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 Fe^Cy^^3NO,Ag-5 + 2HO. 



Nitroprusside of Copper. 



15. This salt is obtained by adding a solution of a copper 

 salt to that of a nitroprusside. 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. 

 25-12 grs, lost in water-bath 2-870, or 11-425 per cent. 



