a New Class of Salts. QTf 



belong to the oblique system. They have been approxima- 

 tively measured by Prof. Miller. 



Symbols: — a 100, c 001, m 1 10; there are 

 besides one or two faces in the zone cm d, 

 the symbols of which have not been found. 



Cleavage a very perfect. 



Angles between normals to faces approximately: — 



o t 



ac 82 

 ma 70 

 mm^ 40 



The values of cm were extremely discordant. In the best 

 crystals, the angle between normals to cu was found to be 

 71° 41'. 



Nitroprusside of calcium is very soluble in water, and in 

 its behaviour to reagents is exactly the same as the soluble 

 nitroprussides already described. By the mean of two ex- 

 periments the crystallized salt lost 17*85 per cent, of water in 

 the water- bath at 212°. 



The salt was analysed by fusion with nitrate of ammonia, 

 the iron and lime being determined in the usual way. 



13*29 grs. gave 4*004 grs. peroxide of iron and 4*698 grs. 

 carbonate of lime. 



8*33 grs. burned with chromate of lead gave 6'56 grs. car- 

 bonic acid and 0*82 water. 



It will be seen that this salt belongs to the class which has 

 dissolved some of the cyanide of iron resulting from its partial 

 decomposition, and that therefore the electro-positive metal 

 is in too small quantity. Allowing for this impurity, which 

 cannot be removed, it is probable that the pure nitroprusside 

 of calcium has the formula Fe^ Cy^^ 3 NO, Csc' + BUO. The 

 loss of water in the water-bath corresponds to 15 equivs., which 

 ought to have given the loss as 1 7 per cent. Inr one experi- 

 ment it lost 17*44 per cent., in another 18-26. We may con- 

 clude that the formula of the crystallized salt is Fe^ Cy^^ 3NO, 

 CaH20HO. 



