260 DE OXIDATION OF FERRIDCYANIDE OP POTASSIUM, 
mentioned mixture of salts, might probably depend solely on 
those three combinations converting the persalf into proto- 
salt, while they leave unaltered the percyanide, the author 
convinced himself that the three bodies mentioned also 
exercise a decomposing action on the solution of the per- 
cyanide. 
It was to be supposed that the bodies which reduced the 
ferridcyanide of potassium to ferrocyanide would likewise 
have a reducing action on the persalts of iron ; the following 
experiments entirely confirm this supposition. For instance, 
if a solution of nitrate of iron be left only for a few minutes, 
or for a shorter time, in contact with arsenic, antimony, bis- 
muth, cadmium, lead, iron, zinc and tin, the solution of per- 
cyanide becomes perceptibly blue. Even copper, mercury 
and silver produce a similar change, but more slowly. ~ 
Whether palladium, platinum and gold are able to effect it 
with time has not yet been ascertained. 
Some protoxides, as for instance that of copper, when 
placed for a short time in contact with the solution of nitrate 
of iron at the ordinary temperature, alters the salt of iron 
in such a manner that the solution of percyanide is render- 
ed blue by it. 
Phosphorus appears to act more rapidly on thejsolution 
of the nitrate of iron than on that of the cyanide. 
Sugar heated only for a short time with a solution of the 
persalt of iron likewise causes it to give a precipitate of 
prussian blue in the solution of the cyanide. Formic acid, 
warmed but for a few instants with the dissolved salt of 
iron, induces the formation of so much protosalt, that on 
mixing this liquid with the percyanide prussian blue is pre- 
cipitated. Citric, acetic and tartaric acids behave in 
a similar manner, but lithic acid is most remarkable from 
its deoxidizing action. If this acid be left in contact only 
for a minute with a solution of the nitrate of iron, the fil- 
tered liquid has acquired the property of precipitating prus- 
