164 



THE ATOMIC WEIGHTS. 



The direct comparison of cadmium and silver was effected by the 

 simultaneous electrolysis, in the same current, of double cyanide solu- 

 tions. Silver was thrown down in one platinum dish, and cadmium in 

 another. The process was not altogether satisfactory, and gave diver- 

 gent results, those which are cited below having been selected by Har- 

 din from the mass of data obtained. I have added in a third column 

 the cadmium jiroportional to 100 parts of silver : 



.0041 



For cadmium we now have the following ratios : 



(I.) Per cent, of Cd in CdO, 87.5064, =b .0003 

 * (2.) Per cent, of CdO in CdC20^, 63.966, rb .0010 



(3.) Per cent, of CdS from CdCjO^, 71.974, =h .0007 



(4.) Per cent, of CdS from CdS04, 69.202, i .0012 



(5.) Ag2 : CdCl2 : : loo : 84.843, i .0260 



(6.) 2AgCl : CdCIj : : lOO : 63.916, rb .0032 



(7.) Ag2 : CdBr^ : : 100 : 126.076, zh .0052 



(8.) 2AgBr : CdBrj : : 100 : 72.438, i .0022 



(9.) Per cent, of Cd in CdClj, 61.244, zh .0010 

 (10.) Per cent of Cd in CdBr^, 41.203, dr .0010 

 (11.) 2Ag : Cd : : 100 : 51.876, ± .0041 



Bucher's single experiment upon the synthesis of the sulphate, although 

 important and interesting, cannot carry weight enough to warrant its 

 consideration in connection with the other ratios, and is therefore not 

 included. 



The antecedent values, for use in computation are — - 



O = 15.S79, zh .0003 S = 31.828,1^.0015 



Ag= 107.108, zb .0031 C = 11.920, zh .0004 



CI = 35.179, ± .0048 AgCl = 142.287, zb .0037 



Br ^= 79.344, zb .0062 AgBr = 186.452, zb .0054 



For the molecular weight of cadmium chloride, two values are now 

 deducible : 



From (5) CdC].^= 181.739, zt .0560 



From (6) " =^ 181. 888, zb .0103 



General mean CdCIj = 181.883, zb .0138 



Hence Cd = 111.525, 



.0138. 



