Combinations of different Metals and Chlorine. 195 
absorption of oxygene by the tin equivalent to 8 cubic inches, 
or (as 100 cubic inches weigh 34.2 grains) to 2.736 grains, 
the protoxide of tin appears to contain 11.95 per cent, of 
oxygene. 
These analyses of the oxides, compared with those of the 
combinations of tin and chlorine, are found very nearly to 
agree. The ratio of oxygene to chlorine in the two first simi- 
lar compounds, the tin being as 55, is as 7.5 to 33.4 ; and in 
the two last, viz. the peroxide and the liquor of Libavius, as 
7.6 to 33.5, or as 35.2 to 67. 
As the black oxide of iron is formed by the decomposition 
of ferrane by a solution of potash, and the red oxiJe by that 
of ferranea, it is evident that these oxides and combinations 
of iron and chlorine should coincide in the proportions of their 
constituent parts. This appears from the analyses* of Dr. 
Thompson to be nearly the case, for iron being as 29.5, the 
oxygene is to the chlorine in the black oxide and ferrane as 8 
instead of 7.5 to 33.6; and in the two others as 8 to 33.6, or 
as 13.2 to 55.5. Here the agreement is less than in other in- 
stances ; but this is not surprising considering the different 
estimates of the proportions of oxygene in the oxides of iron, 
and the difficulty of ascertaining them correctly. 
The yellow oxide of lead and the white oxides of antimony, 
bismuth, zinc, and arsenic are formed, when the combinations 
of these metals and chlorine are decomposed by a solution of 
potash. But on comparison with the best analyses of the 
oxides, there is not, excepting in the case of zinc and arsenic, 
that coincidence of proportions which might be expected. 
Zinc being as 34.5, the oxygene in the oxide from the analysis 
* Nicholson’s Journal, Vol. XXVII. p. 375. 
C C 2 
