A NEW CLASS OF SALTS. 
503 
The values of cu 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 experiments 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. carbonic acid and 0*82 water. 
Iron . . . 
. . . 21*09 
5 
140 
Calculated. 
21*11 
Calcium 
. . . 14*14 
5 
100 
15*08 
Carbon . . 
. . . 21*47 
24 
144 
21*71 
Hydrogen . 
. . . 1*09 
5 
5 
0*75 
Nitrogen 
■ * '1 42*21 
r 210 
210-) 
41*35 
Oxygen . . 
1 8 
64 J 
100*00 
663 
100*00 
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 
Fcg Cyi 2 3NO, Cag-f-SHO. The loss of water in the water-bath corresponds to 
15 equivs., which ought to have given the loss as 17 per cent. In one experiment 
it lost 17*44 per cent., in another 18*26. We may conclude that the formula of 
the crystallized salt is Fcg Cy^g 3NO, Ca 5 -}- 20 HO. 
Altered Nitroprusside of Barium. 
22. When a solution of nitroprusside of barium is boiled, it deposits a brown pre- 
cipitate containing both iron and barium*. The solution now crystallizes either in 
pyramidal or in prismatic crystals, that is, in the first state when crystallized slowly, 
in the second when deposited quickly from a hot solution. It is now found that the 
salt is inconstant in composition, different preparations giving very discordant results. 
The salt is however peculiarly difficult to dry, having to be kept in the water-bath for 
days before it ceases to lose weight ; it abstracts water when dried most speedily from 
the atmosphere. 
It is found that the carbon is increased in a marked degree. The following two 
specimens were made at different times and analysed. Analyses I. and II. were made 
* The barytes used in decomposing the nitroprusside of copper was that made by boiling peroxide of man- 
ganese with sulphuret of barium. It always contains a little hyposulphite, and the brown precipitate was 
found to contain sulphate of barytes. 
3 T 2 
