A NEW CLASS OF SALTS. 
505 
greater or less quantity of a foreign substance prevailing in all, and producing results 
so very discordant. In the first two portions analysed the barium is to the carbon 
(37‘01 ; ]7'79) almost exactly as 1 equiv. : 5|equivs., and the iron is to the carbon, 
sensibly though not so exactly, in the same proportion. In analysis VI., the iron is 
to the carbon as 28 : 33*7, or rather more than 1 : while the barium is to the carbon 
as 1 : 6. Again, in analyses IV. and V., the iron is to the carbon as 1 : 5, and the 
barium to the same element 1 : 5^. 
Finally, it will be seen further on that the silver salt made from these altered salts 
of barium do not contain this excess of carbon. The filtrate from the silver salts 
yields on evaporation and incineration a small quantity of a black ash, but the quan- 
tity being so small the nature of the substance could not be ascertained. We can 
scarcely suppose that it is a ferrocyanide, because we should have expected to have 
it precipitated by nitrate of silver, even though it could not be recognized by its usual 
tests. It would be useless without further information to speculate upon the probable 
nature of the impurity. Sufficient however has been shown to prove that the most 
complicated results may attend the analysis of specimens of nitroprusside of barium 
prepared from solutions which have been heated and thus partially decomposed. 
Altered Nitroprusside of Sodium. 
23. The previous analyses of the crystallized nitroprussic acid and of the nitro- 
prussides of ammonium and barium, and the composition of the silver salts prepared 
from them, show a want of accordance between the iron in the electro-negative con- 
stituent and the metal in the electro- positive one. The iron in all these cases is 
about half a per cent, in excess, therefore not sufficient to be considered as being in 
atomic proportion. It was thought, from the very distinct crystallization of the 
sodium salt, that this excess might not accompany it if prepared from the respective 
silver salts of the above compounds. Accordingly the silver salt was decomposed 
by an equivalent quantity of hydrochloric acid. The resulting solution was neutral- 
ized with carbonate of soda and crystallized. Analyses I. and II. were made on a 
salt thus prepared from crysfallized nitroprusside of barium. Analysis III. on a salt 
similarly made from nitroprusside of ammonia. Again, when we refer to the action 
of caustic soda on the nitroprussides, it was obvious that by using a less quantity of 
the alkali than sufficed to effect the complete decomposition, a nitroprusside with a 
similar impurity in solution was to be expected. 
Analysis IV. was made on a specimen thus prepared, and its accuracy is confirmed 
by a future analysis of a silver salt. 
J I. 13‘695 grs. gave 3‘72 grs. peroxide of iron. 
1 II. 20-93 grs. gave 5-72 grs. peroxide of iron and 9*93 grs. sulphate of soda. 
III. 15-35 grs. gave 4-25 grs. peroxide of iron and 7*10 grs. sulphate of soda. 
IV. 11-13 grs. gave 3 07 g’l’s. peroxide of iron and 5-06 grs. sulphate of soda. 
The combustions were made with chromate of lead. 
