194 Mr,]. Davy’s Account of some Experiments on the 
33.77, instead of 33 .6 ; and in the two last as 7.5 to 33 .6, or 
as 15 to 67.2. Coincidences as near as might be reasonably 
expected. 
There is not the same agreement between M. Proust’s 
analyses of the oxides of tin and the preceding ones of the 
combinations of this metal and chlorine. This discordance 
induced me to repeat my analyses, and obtaining the same 
result as at first, I directed my attention to the oxides of tin, 
and made the following experiments to ascertain the propor- 
tion of their constituent parts. 
42.5 grains of tin, which had been precipitated from the 
muriat of this metal by zinc, were heated with nitric acid in a 
platina crucible, and slowly converted into peroxide ; the acid 
and water were driven off’ by gentle evaporation at first, and 
afterwards by a strong red heat continued for a quarter of an 
hour. The peroxide thus produced was of a light yellow 
colour, and being very gradually dried, it was semi-transpa- 
rent, and hard enough to scratch glass ; it weighed 54.25 grains. 
Hence, as 42.5 grains of tin acquire, on conversion into per- 
oxide, 1 1 .75 grains of oxygene, this oxide appears to contain 
21.66 per cent, of oxygene, just the quantity found in the 
native oxide by Klaproth, instead of 28, the proportion stated 
by Proust. 
M. Berthollet, jun. has shewn that M. Proust’s estimate 
of 20 per cent, of oxygene in the protoxide is incorrect. To 
ascertain the true proportion, 20 grains of tin were dissolved 
in strong muriatic acid, in a retort connected with a pneumatic 
apparatus, and without the assistance of heat ; 16 cubic inches 
of hydrogene gas were produced. (Barom. 30, thermom. 60) 
as the production of this quantity of hydrogene indicates an 
