Chemistry and Physics. 113 
13. O 
Piayrair, (Phil. Trans. for 1849, part 2d3 L., E. and D. Phil. Mag., 
March, April, and May, 1850.)—Hitherto but little has been known in © 
regard to the action of nitric acid upon the ferrocyanid of potassium. 
The most remarkable observation on the product of this reaction was_ 
that when added to a solution of alkaline sulphid, a magnificent purple 
d 
m the Nitroprussids, a new class of Salts; by Dr. ines) 
White substance which proves to be ovamid. ‘To form i 
sodium, which is more readily procured than the salt tassium, 
the solution i8 neutralized with carb. soda, boiled and filtered from the 
dark-green or sometimes brown precipitate which forms. Concent 
with soluble sulphids. The author proposes this as the mos ; 
test known for that class of compounds. The beautiful purple color is © 
however very fugitive. : 
_ The precipitates formed by the nitroprussids are salmon-colored 
Jn the protosalts of iron, light green with salts of copper, and not very 
Striking with several other metals. ith persalts of iron, salts of tin 
and mercury, an J neutral salts of lead, no change 1s produced. 
ALES Vol. XI, No. 31.—Jan,, 1851. 15 
