Perhydrosulphocyantc Acid. 53 
Besides this neutral compound, this chemist has formed 
another, by precipitating a solution of the acid with basic ace- 
tate of lead. It is composed of 2 atoms of the neutral salt 
combined with 1 atom of oxide of lead. 
C4 Nt S§ Pb? O = 2 (C? N? S* + PbS) + PbO. 
If hydrochloric acid gas is passed through a saturated solu- 
tion of the sulphocyanide of potassium artificially cooled, large 
quantities of the perhydrosulphocyanic acid are formed, with 
hydrocyanic acid, formic acid, carbonic acid, sulphuret of 
carbon and ammonia; but no sulphuretted hydrogen. Sul- 
phuret of carbon and carbonic acid sometimes are produced 
in very small quantities, sometimes not at all. 
3 atoms of hydrosulphocyanic acid are decomposed by 
hydrochloric acid into 2 atoms of perhydrosulphocyanic acid 
and 1 atom of hydrocyanic acid. The hydrochloric acid 
removes the water necessary for the existence of the hydro- 
sulphocyanic acid. The formation of carbonic acid and the 
sulphuret of carbon depends on another decomposition. 1 
atom of hydrosulphocyanic acid takes 2 atoms of water, 
and forms 1 atom carbonic acid, 1 atom sulphuret of carbon, 
and 1 atom of ammonia. If the solution of sulphocyanide of 
potassium be not sufficiently cool nor saturated, this decompo- 
sition takes place. ‘The best proportions are 1 part of the 
salt and 5 parts water. 
When heated to 150° perhydrosulphocyanic acid begins to 
be decomposed, forming sulphuretted hydrogen and hydro- 
sulphocyanic acid. When the temperature is raised to 200°, 
sulphur, and sulphuret of carbon are given off; if still greater 
heat is applied, ammonia is formed and mellon is left. 
Decomposition of Sulphocyanide of Potasscum by Chlorine in 
the presence of Water. 
The experiments of Parnell * and Bengiesser have been re- 
peated by Vélekel. When a stream of chlorine is passed 
through a concentrated solution of sulphocyanide of potas- 
sium, the latter being kept cool, there are formed sulphuric 
acid, hydrocyanic acid, or cyanogen, and a yellowish red body, 
but no carbonic acid nor ammonia. 
This body is insoluble in water, alcohol, and zther. It is 
dissolved with difficulty by diluted potash ley ; when the mix- 
ture is heated the solution is easily effected, and is of a deep 
red colour. From this solution acids reprecipitate it un- 
altered. ‘The analysis made by Volckel of this body agrees 
* The experiments here referred to will be found in Mr. Parnell’s pa- 
per on sulphocyanogen, Phil. Mag. S. 3. vol. xvii. p. 249. 
