E. A. Partridge — Atomic Weight of Cadmium. 383 



phide was placed in the weighing tube, allowed to cool and 

 weighed. In every case the sulphide was reheated in the 

 stream of hydrogen sulphide. There was never any volatiliza- 

 tion of cadmium sulphide, as the weight always remained the 

 same, although in some experiments the sulphide was heated 

 three times as long as in others. Moreover there was never 

 any sign of volatilization either on the boat or on the tube. 

 Ten experiments by the above method gave the following 

 results : 



Series III. 







Weight of 



cadmium oxalate 



taken. 



Weight of 



cadmium sulphide 



found. 



Atomic 

 weight. 



1 





. 1-57092 



1-13065 





111-812 



? 





_ 1-73654 



1-24979 





111-786 



3 





. 2-19276 



1-57825 





111-824 



4 





. 1-24337 



•89492 





111-823 



5 





. 1-18743 



•85463 





111-807 



6 





. 1-54038 



1-10858 





111-771 



7 





. 1-38905 



•99974 





111-808 



R 





. 2-03562 



1-45617 





111-833 



9 





. 2-03781 



1-46658 





111-774 



10 



al 



1-91840 



1-38075 



111 



11 1-814 



Tot 



16-85228 

 value ! . . 



12-12906 



(111-8050) 



•805 





Mean 





Maxii 



Minirr 



Differ 

 Probr 



nnm 





111 

 111 



•833 





mm 





•771 





ence . . 











•062 





ible error . . . 





•009 



The mean of the three series gives 111-8015 as the atomic 

 weight of cadmium, with O = 16. 



The following is a description of the methods and apparatus 

 used in the weighings: In the experiments by Lenssen's 

 method two crucibles were used, one as a counterpoise. This 

 dummy was treated in every respect in the same manner as the 

 crucible containing the material operated upon. For weighing 

 the crucibles, small beakers, with glass covers ground on, were 

 provided. These beakers were adjusted so that their weights 

 were approximately equal. The balance being provided with 

 two riders, one of them was used to obtain adjustment with 

 the beakers on the pans, while the other was used in the actual 

 weighing after the crucibles were introduced. The beakers 

 were never touched with the hands, but were taken in and out 

 of the balance case by means of tongs, and the crucibles were 

 introduced into the beakers with platinum forceps. The adjust- 

 ment of the balance with the beakers on the pans was tested 



