182 THE ATOMIC WEIGHTS. 



Berzelius 80.042, d= .005 



Willi, 1st series 80.015, ± .041 



" 2d " 80.028, d= .004 



General mean 80.035, it .003 



Hence Te = 127.98(), ± .035. 



By von Hauer's process, the analysis of TeBr4.2KBr, 

 AVill's figures give results ranging from Te = 126.07 to 

 127.61. Reduced to a common standard, 100 parts of the 

 salt yield the quantities of AgBr given in the third column : 



1.70673 grm. KjTeBrg gave 2.80499 grm. AgBr. 164.349 



1.75225 " 2.88072 " 164.39S 



2.06938 " 3-40739 " i64-*357 



3.29794 " 5-43228 " 164.717 



2.46545 •' 4-05742 " 164.571 



Mean, 164. 53S, i .048 



Combined with von Hauer's mean, 164.408, dz .045, this 

 gives a general mean of 164.468, =b .033. Hence Te = 

 127.170, ± .173. 



The two independent values for Te combine thus : 



From TeOj Te r= 127.986, d= .035 



" TeKjBrg " = 127.170, dz .173 



General mean " = 127.960, ifc .034 



If O = 16, Te = 128.254. 



A careful consideration of the foregoing figures, and of 

 the experimental methods by which they were obtained, 

 will show that they are not absolutely conclusive with re- 

 gard to the place of tellurium under the periodic law. The 

 atomic weight of iodine, calculated in a previous chapter, is 

 126.557. Wills' values for Te, rejecting his first series as 

 relatively unimportant, range from 126.07 to 128.00 ; that 

 is, some of them fall below the atomic weight of iodine, 

 although none descend quite to the 125 assumed by Men- 

 del ejeflf. 



In considering the experimental methods, reference may 

 properly be made to the controversy regarding the atomic 

 weight of antimony. It will be seen that Dexter, estima- 

 ting the latter constant by the conversion of the metal 



