Sulphur and Phosphorus. 251 
with hydrogens, according to different circumstances of the 
process. I shall now refer to such of these circumstances as I 
have been able fully to investigate. 
The able researches of Dr. Thomson have shewn that sul- 
phur, in its usual state, contains small quantities of acid matter ; 
and though, in my first experiments, I conceived that by em- 
ploying chrystalized native sulphur, which had been recently 
sublimed in nitrogene, I should avoid the presence of any 
foreign matter, yet I am inclined to believe that this is not the 
case ; for by subliming some similar sulphur in nitrogene, I 
find that litmus paper placed in the upper part of the retort is 
slightly reddened. 
When potassium is made to unite with sulphur, if the retort 
employed is not lined with sulphur, some of the potassium is 
destroyed by acting upon the glass ; and when large quan- 
tities of sulphur are used, it is very difficult to decompose the 
whole of the sulphuret of potassium by an acid : sulphuretted 
hydrogene likewise is soluble in muriatic acid ; and this cir- 
cumstance led me to under-rate the quantity of sulphuretted 
hydrogene given off in experiments of this kind.* 
In acting upon sulphuretted hydrogene by potassium in my 
early experiments, I used large quantities of the gas and of 
the metal ; and in these cases I have reason to believe that 
the violence of the combustion, occasioned the decomposition 
* This circumstance has been pointed out by M. M. G ay Lussac and Thenard; 
in a paper printed in the Journal de Physique for December, in which these gentle- 
men endeavour to shew that, whether potassium has been acted upon by large or smalL 
quantities of sulphur, and under all circumstances, it evolves a quantity of gas exactly 
equal to that which it produces by the action of water. I have been able to gain no 
results so precise on this subject. I have in another place (the same journal in which* 
their memoir has appeared) offered some observations on their enquiries. 
