Comlinations of different Metals and Chlorine, ^c. 169 



part by weight of hydrogen, for example, 7'5 of oxygen 

 luiite to form water, and 33-6 of chlorine unite with the 

 same proportion to produce muriatic acid gas. To judge 

 therefore of the accuracy of the analyses of the preceduig 

 combinations of the metals and cldorine, it is only neces- 

 sary to coinpare them with the analyses of the oxides of 

 the same metals. If the two agree, there will be reason to 

 consider then, both correct; bul should they disagree, there 

 is equal reason for supposing one or both of them to be 

 wrong. 



Thus, as the orange oxide of copper is analogous to cu- 

 prane and the brown oxide to cupranea, the oxygen and 

 chlorine should be to each other in these compounds as 

 7-0 to 33-6. And from comparison of my analysis, with 

 those of Mr. Chenevix and M. Proust, it appears, that in 

 the two first, copper bcins as 60, the oxygen is to the 

 chlorine as 7-79, instead of To to 33-77, instead of 33-6; 

 and in the two last as 7-5 to 33'6, or as 13 to 67-2. Co- 

 incidences as near as might be reasonably expected. 



There is not the same agreement between M. Proust's 

 analy>es of the oxides of tin and the preceding ones of the 

 comb-nations of this metal and chlorine. This discoidance 

 induced me to repeat my analyses ; and obtaining the same 

 result as at first, I directed my atlfniion to the oxides of 

 tin, and made the following experiments to ascertain the 

 proportion of their constituent parts. 



42-5 srains of tin, which had been precipitated from the 

 muriat or this metal by zinc, were healed with nitric acid 

 in a |)!atina crucible, and slowly converted into peroxide; 

 the acid and water uere 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 \tllow colour; and being very gradually dried, it was 

 semi-transparent, and hard enough to scratch glass; it 

 weighed 54-iI5 grains. Hence, as 42-3 grains of tjn ac- 

 quire, on conversion into peroxide, J 1-75 grains of oxygen, 

 this oxide appears to contain 21-6() percent, of ^oxygen, 

 just the <]u:nuitv found in the native oxide by Klaproth, 

 instead of 28, the proportion stated by Prou?t. 



M. Beiiholltt, jun. has shown that M. Proust's estimate 

 of 20 jitr cent, of oxygen in the protoxide is incorrect. 

 To ascertain the true proportion, 20 grains of tin were dis- 

 solved in strung muriatic acid in a retort connected w ith a 

 f)iieuiiiatic ap] anuus, and without the assistance of heat ; 

 If) cubic inrhes of hvdrogen gas were produced, (rarom. 

 30, thennom. 60.) As the production of this quantity of 



hydrogen 



