276 THE ATOMIC WEIGHTS. 



instead of being extracted from metallic tellurides, was derived from 

 Japanese native sulphur, in which it exists as an impurity. This differ- 

 ence of origin in the material studied gives the chief interest to the 

 investigation. The data are as follows : 



TeBr^. Ag. Ratio. 



4. 1812 4-0348 103.628 



4.3059 4-1547 103.639 



4.5929 4-4319 '03.633 



Mean, 103.633, ± .0023 

 Brauner found, 103.644, ± .0018 



General mean, 103.640, ± .0014 



Now, to sum up, the subjoined ratios are available for computing the 

 atomic weight of tellurium : 



(I.) Percentage Te in TeOj, 80.001, d= .0025 

 (2.) Percentage Te in HgTeOg, 55.508, =b .0068 

 (3.) Percentage TcO.^ in HgTeOg, 64.440, zb .0024 

 (4.) Ag^ : TeBr^ : : loO : 103.640, ± .0014 

 (5.) K2TeBrg : 6AgBr : : 100 : 164.468, zb .0330 

 (6.) TeOa : O : : lOO : 10.068, ± .0100 



To reduce these ratios we have — 



O = 15.879, ± .0003 K =^ 38.S17, ± .0051 



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



Br r= 79.344, =h .0062 



For the atomic weight of tellurium six values appear, as follows: 



From (i) Te = 127.040, zh .0165 



From (4) " = 126.650, zt .0302 



From (5) " == 126.502, ziz .1430 



From (2) " = 126.303, jz .0246 



From (3) " = 126.209, ziz .0138 



From (6) " = 125.960, zh - 1574 



General mean Te = 126.523, zt .0092 



If = 16, Te = 127.487. 



A careful consideration of the foregoing figures, and of the experi- 

 mental methods by which they were obtained, will show that they are 

 not absolutely conclusive with regard to the place of tellurium under 

 the periodic law. The atomic weight of iodine, calculated in a previous 

 chapter, is 125.888. Wills' values for Te, rejecting his first series as rela- 

 tively unimportant, range from 125.40 to 127.32 ; that is, some of them 

 fall below the atomic weight of iodine, although none descend quite to 

 the 125 assumed b}'' Mendelejeff. 



Some of Brauner's data fall even lower; and the same thing is true in 



