ZINC. 155 



For computing the atomic weight of zinc we now have these ratios: 



(i.) Per cent. Zn in ZnO, 80.317, .0008 



(2.) Per cent. ZnO in ZnSO 4 , 50.413, rb .0020 



(3.) H 2 O : Zn : : 100 : 366.319, .088 



(4.) 2CO 2 : Zn : : 100 : 93.169, rb -OI2 



(5.) H : Zn : : I : 65.079, .0036 



(6.) Ag 4 : K 2 ZnCl 4 : : 100 : 66. in, .0023 



(7.) Ag 2 : Zn : : 100 : 30.318, .0077 



(8.) Cu : Zn : : 100 : 103.22, =b .0261 



(9.) Ag 2 : ZnBr 2 : : 100 : 104.38, rb .0007 



(10.) 2AgBr : ZnBr 2 : : 100 : 59.962, rb .0004 



The antecedent atomic weights, with H = 1, are 



O 15.879, rb .0003 C = 11.920, rb .0004 



Cl = 35.179, .0048 S = 31.828, rb .0015 



Br = 79.344, rb .0062 Cu 63.119, rb .0015 



Ag = 107.108, rb .0031 AgBr = 186.452, rb .0054 

 K = 38.817, rb .0051 



With these data, combining ratios 9 and 10 into one (see preceding 

 paragraphs), we have nine independent values for the atomic weight of 

 zinc, as follows : 



From (i) Zn = 64.795, d= .0030 



From (2) " = 64.909, rb .0073 



From (3) " = 65.494, rb .0019 



From (4) " =65.521, rb .0115 



From (5) " = 65.079, rb .0036 



From (6) " = 64.891, rb .0253 



From (7) " = 64.947, rb .0166 



From (8) " =65.151, .0166 



From (9) and (10) " = 64.912, rb .0133 



General mean of all Zn = 65.152, .0014 



With O = 16 Zn = 65.650 



Of these values, Nos. 3 and 4, representing Favre's work, are unques- 

 tionably far wrong. Rejecting them, the general mean of the remaining 

 seven values becomes 



Zn = 64.912, .OO2I. 



If = 16, this gives Zn = 65.407. These figures are identical, except 

 as regards the lower probable error, with the result deduced from Rich- 

 ards and Rogers' determinations alone, and they may be taken as 

 satisfactory. 



