combinations of platinum. 119 
When this compound is decomposed by heat in close 
vessels over water or mercury, it yields a grey sulphuret 
of platinum,* nitrogen, sulphureous, carburetted hydrogen 
and carbonic acid gases, carbonate of ammonia, and an oily- 
like fluid. This compound of sulphate of platinum and gela- 
tine, when dried at a heat just above that of boiling water, 
afforded, by its decomposition in two experiments, half its 
weight of platinum ; and if my former statement of the com- 
position of sulphate of platinum is correct, 10 o grains of the 
above compound will consist of about 
56-11 oxide of platinum, 
20-02 sulphuric acid, 
23-87 gelatine and water. 
10000 
6. On the sulphate of platinum, as a test for gelatine. 
As I found l hat minute quantities of gelatine in solution, 
were readily detected by the sulphate of platinum, I made 
some experiments to ascertain the efficacy of this substance as 
a test for gelatine, and I am inclined to think it merits a de- 
cided preference over the re-agents at present used by che- 
mists for this purpose. The best known substances for de- 
tecting the presence of gelatine are, I presume, those which 
contain the tanning principle, as the infusions of oak-bark, 
nutgalls, catechu, &c. And a variety of gelatine, isinglass, 
(as is well known), is employed to ascertain the quantity of 
* In the “ Annales de Chimie,” Sec. Tome V., M. Vauquemn treats of the 
sulphuret of platinum as a new compound which he had formed ; but I published 
an account of it in the Philosophical Magazine, in the year 1812. 
