154 



THE ATOMIC WEIGHTS. 



At the end of the same paper, Richards alone gives two more series of 

 determinations made upon zinc bromide prepared by the action of pure 

 bromine upon pure electrolytic zinc. The bromide so obtained was 

 further refined by sublimation or distillation, and dried by heating in a 

 stream of carbon dioxide and gaseous hydrobromic acid. Thus was 

 ensured the absence of basic salts and of water. The weights and results 

 found in the two series were as follows : 



ZnBr.,. 

 6.23833 

 5 26449 

 9.36283 



ZnBr.^. 



2.65847 

 2.30939 

 5.26449 



Series C. 



5.9766 

 5-0436 

 8.9702 



Series D. 



AgBr. 



4.43358 

 3-85149 

 8.77992 



Ratio. 



104.379 

 104.380 



104.377 

 Mean, 104.379, zt .0007 



Ratio. 



59.962 

 59.961 

 59.961 



Mean, 59.961, ± .0004 



In some details of manipulation these series differ from those given 

 by Richards and Rogers jointly, but their minutiae are not essential to 

 the present discussion. 



Combining these several series, we have — 



For Ag.^ : ZfiBr.j^ : : 100 : x. 



Series B 104.392, ± .0054 



Series C 104.379, ± .0007 



General mean 104.380, ± .0007 



For 2 AgBr : ZnBr.^ : : 100 : x. 



Series A 59.975, db .0034 



Series B 59.967, zt .0027 



Series D 59.961, zfc .0004 



General mean 59.962, zb .0004 



From the Ag ratio ZnBr.^ = 223.599, rh .0066 



From the AgBr ratio " = 223.601, zh .0066 



General mean ZnBr.^ i^ 223.600, zfc .0047 



And Zn t= 64.912, zh .0133 



