NEW MODE OF CHEMICAL ANALYSIS. 
43 
of a cubic galena with large faces, which did not contain any 
sensible quantity of foreign matter. The peroxide of manga- 
nese used did not contain any baryta. Examined by itself, 
it gave for one gramme, 2 gr. 35 of sulphate of baryta, cor- 
responding to gr. 16 of oxygen. 
One gramme of galena, finely powdered, was mixed with 
three grammes of peroxide of manganese. This mixture was 
treated by hydrochloric acid, with proper precautions. The 
galena was completely dissolved without depositing any sul- 
phur. The sulphate of baryta resulting from the reaction of 
an excess of chlorine upon a solution of sulphurous acid, mixed 
with hydrochlorate of baryta, weighed, after calcina- 
tion, 3 gr. 19 
The three grammes of peroxide of manganese, treat- 
ed by itself, with hydrochloric acid, should yield 
sulphate of baryta, . . . . . . 7 gr. 05 
The whole quantity of oxygen absorbed, corresponds, 
then, to sulphate of baryta, . . . . 3 gr. 8G 
And is, consequently, equivalent to . . .0 gr. 265 
On the other hand, by precipitating the solution of lead, by 
means of the hydrochlorate of baryta, I obtained, sulphate of 
baryta 0.97; that is to say, very nearly one-fourth of 3 gr. 86. 
This agreement allows us to conclude, independently of every 
theory of the composition of the acids and sulphur, that there 
is a simple agreement between the quantities of oxygen, 
which sulphur and sulphurous acid take in passing to the state 
of sulphurous acid; and on the other hand, that there exists 
equally a simple agreement between the quantity of oxygen 
absorbed by the sulphur, to pass to the state of sulphurous 
acid, and that which the lead requires to be changed into 
protoxide. 
But as we possess the knowledge of the composition of 
the sulphate of baryta, and that of the acids of sulphur, we 
may say: 
Sulphate of baryta, gr. 97, contains sulphuric acid,0 gr. 331 
composed of sulphur, gr. 132, and oxygen, gr. 199. 
Or the whole quantity of oxygen absorbed is gr. 265. 
