A NEW CLASS OF SALTS. 
511 
by distillation vvith caustic soda, collected in muriatic acid and determined as chlo- 
ride of platinum and ammonia. This process did not however give constant results 
in my hands, probably from the difficulty of preventing the escape of nitric oxide on 
adding an acid to the nitrite. The nitrite was therefore determined by loss. In one 
case only did I, by the above process, obtain a result approaching the quantity of 
nitrite in solution. 
17-24 grs. of nitroprusside of sodium were dissolved in water, the solution was 
boiled and caustic soda added, keeping the solution distinctly alkaline after ebullition 
had continued for some time. It yielded 0-92 gr. peroxide of iron, and 14‘85 grs. 
ferrocyanide of sodium ; the residual liquid, treated according to Nesbit’s plan, only 
gave 2*57 grs. platinum salt. 
Iron precipitated 3'73 per cent. 
Iron in prusside 15’08 per cent. 
18-81 
Hence all the iron, except about 0-5 per cent., is found in the oxide of iron and in 
the prusside ; the remainder is probably in the minute quantity of pink salt alluded 
to above. The carbon contained in the prusside amounts to 20-3 ; so that the total 
quantity of cyanogen has gone down in that form, the carbon in the nitroprusside 
being 20-0 per cent. 
It will be seen that the iron precipitated as peroxide of iron is one-fourth that re- 
tained in the ferrocyanide. The following equation expresses the transformation : — 
2(Feg Cyi 2 3NO, Nag) + 9 NaO=: 4 (Fe 2 Cyg Na 4 ) +3NaO, N 03 - 1 -Fe 2 O 3 -I- 3 N. 
Or expressed in another way, — 
4 equivs. ferrocyanide of sodium . . . Fcg Cy 24 Na 4 g 
3 equivs. nitrite of soda Nag Ng O 42 
1 equiv, peroxide of iron Fe 2 O 3 
3 equivs. nitrogen Ng 
2 equivs. nitroprusside+9 of soda=Fe 4 o Cy 24 Na 49 Ng Ojg 
The first change is obviously to form ferrocyanide of sodium, 6 equivs. of oxygen 
passing over to the nitrous oxide; this, with the oxygen in the latter, would make 
4 equivs, nitrous acid ; but the 2 equivs. of iron liberated require 3 of oxygen to 
form peroxide, which it receives at the expense of the nitrous acid, leaving therefore 
3 equivs. of that acid to unite with soda, the remaining 3 equivs of nitrogen escaping 
as a gas. During the ebullition no ammonia can be detected, either by smell or by 
turmeric paper. 
Section V. — Action of an Alkaline Sulphide on a Nitroprusside. 
27 . It has been repeatedly mentioned, that when solutions of nitroprusside of 
potassium or sodium and of the corresponding sulphides are mixed together, the most 
magnificent purple colour is produced. This colour however is very transitory and 
cannot be preserved in an aqueous solution. The purple or blue compound may 
3 u 2 
