CbMBlNATIONS OF OXIMURlATlC ACID AND METALS. 129 



As the production of this quantity of hidrogen indicates an 

 absorption of oxigen 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 irpQ per cent of oxigen. 



These analyses of the oxides, compared with those of the 

 combinations of tin and chlorine, are found very nearly to 

 agree. The ratio of oxigen to chlorine in the first two simi- 

 lar compounds, the tin being as 55, is as 7-5 to 33'4; and in 

 the last two, viz. the peroxide and the liquor of Libavius, as 

 7-6 to 33-5, or as 15-2 to 67. 



As the black oxide of iron is formed by the decomposition of iron; 

 of ferrane by a solution of potash, and the red oxide 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 

 oxigen is to the chlorine in the black oxide and ferrane as 8 

 instead of '^•5 to 336; and in the two others as 8 to 33*6, or 

 asl3'2 to 55*5. Here the agreement is less than in other 

 instances ; but this is not surprising, eonsidering the different 

 estimates of the proportions of oxigen in the oxides of iron, 

 and the difficulty of ascertaining them correctly. 



The yellow oxide of lead, and the white oxides of antimony, of other me- 

 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 oxigen in the oxide, from the analysis of zinc; 

 of Proust, is to the chlorine as 7-5 to 34*4 ; and the arsenic of arsenic; 

 being as 21'9, the oxigen, from the analysis of the same che- 

 mist, is to the chlorine as 7'3 to 33'6, The analyses of the 

 oxides of the other metals being at variance with those of the 

 chlorine combinations, I was induced to make the following 

 experiments, with the hope of discovering the cause of the 

 difference. 



100 grains of lead, which had been precipitated from the of lead ; 

 nitrate of lead by zinc, were dissolved in nitric acid, and thrown 

 down by carbonate of potash. This precipitate of carbonate of 

 • Nichelson's Journal, vol. XXXVIl, p. S75. 



Vol. XXXIII, No. 152.--OCT0BER, 1812. K lead 



