1819.] Sulphuretted Chyazic Acid. 105 
obtain prussiate of lime, which forms prussian blue with ferru- 
ginous solutions. : isis 
When sulphuretted chyazic acid is poured into a vessel filled 
with chlorine gas, the temperature rises “considerably. The 
whole of the sulphur is converted into sulphuric acid, and of 
course no sulphur is precipitated. 
Thus it appears that the action of chlorine upon sulphuretted 
chyazic acid consists in converting the sulphur into sulphuric 
acid, and setting the prussic acid at liberty. It is necessary to 
employ a slight excess of chlorine in order to acidify the whole 
of the sulphur ; but ifthe proportion used be too great, it would 
combine with the prussic acid when set at liberty. 
The opinion of Mr. Porrett, that sulphuretted chyazic acid is © 
a compound of prussic acid and sulphur, is not so absurd as 
M. Grotthuss conceives it to be; for can it be said that the 
chlorine formed prussic acid? This would be a thing without 
example in chemical science. 
The sudden death which sulphuretted chyazic acid produces 
ip animals seems still further to favour ¢he notion, that it is not 
merely the elements, but the prussic acid itself, which acts. It 
is a most striking fact that prussic acid, when it combines with 
sulphur, loses its most remarkable properties. 
Nitric or nitrous acid does not precipitate sulphur from 
sulphuretted chyazic acid. All the sulphur is converted into 
sulphuric acid, and the prussic acid becomes free. Concentrated 
sulphuric acid is the only acid which precipitates sulphur from 
sulphuretted chyazic acid,.* 
Action of Iodine. 
When sulphuretted chyazic acid was boiled with iodine, there 
passed into the receiver, which contained lime water, a quantity 
of prussic acid. The liquid which remained in the crucible had 
a reddish brown colour, and was very acid, but did not contain 
prussic acid. When this liquid was neutralized by ammonia, it 
became colourless. It was precipitated red by corrosive subli- 
mate ; orange yellow by acetate of lead; and green by proto- 
nitrate of mercury. The sulphuretted chyazic acid of course 
had been decomposed, and hydriodic acid formed. 
On an analogous Property between Sulphuretted Chyaxic Acid and 
Meconic Acid. 
Sulphuretted chyazic acid, when mixed with ferruginous salts, 
produces exactly the same appearances as meconicacid. Neither 
of these acids occasions any change of colour in the protosalts ; 
but both of them dissolve the peroxide of iron, and form with it 
* When I placed sulphuretted chyazic acid in the circuit of a Voltaic battery 
of 50 pair of plates, I observed at the negative pole a considerable disengagement 
of gas, while sulphur was deposited round the positive pole, 
