ZINC. 155 



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



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

 (2,) Per cent. ZnO in ZnSO^, 50.413, zh .0020 

 (3.) H.p : Zn : : loo : 366.319, i .088 

 (4.) 2CO2 : Zn : : 100 : 93.169, zb .012 

 (5.) H : Zn : : I : 65.079, ± .0036 

 (6.) Ag^ : K.^ZnCl^ : : 100 : 66. ill, ± .0023 

 (7.) Ag^ : Zn : : lOO : 30.318, =b .0077 

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

 (9.) Agj : ZnBrj : : loo : 104.38, rb .0007 

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



The antecedent atomic weights, with H = 1, are — 



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



CI = 35.179, ± .0048 S = 31.828, lb .0015 



Br = 79.344, lb .0062 Cu = 63.119,^.0015 



Ag= 107.108, =b .0031 AgBr= 186.452, zb .0054 

 K = 3S.817, lb .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, =t .0030 



From (2) " =: 64.909, zb .0073 



From (3) " = 65.494, zb .0019 



P'rom (4) . . . . " = 65.521, zb .0115 



From (5) " = 65.079, zb .0036 



From (6) " = 64.891, dz .0253 



From (7) ....." " ^ 64.947, zb .0166 



From (8) "= 65.151, zb .0166 



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



General mean of all Zn ^ 65.152, zb .0014 



With 0=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, zb .0021. 



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 

 satisfactor3^ 



