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



allowed to cool and weighed. 



T 



en experiments 



by this met 



gave the following results : 













Series II. 









Weight of 



cadmium sulphate 



taken. 



Weight of 



cadmium sulphide 



found. 



Atomic 

 weight. 



1 



... 1-60514 





1-11076 





11 1-793 



2 



... 1-55831 





1-07834 

 1-15669 





111-789 



3 



... 1-67190 



111-790 



4 



... 1-66976 





1-15554 





111-818 



5 



. ... 1-40821 





•97450 





111-801 



6 - 



. . . 1-56290 





1-08156 





111-806 



7 



... 1-63278 





1-12985 





111-778 



8 



... 1-58270 





1-09524 

 1-06481 





111-797 



9 



... 1-53873 



111-796 



10 . 



1-70462 





1-17962 





111-801 



Total 



.. 15-93505 



11-62717 



(111-7969) 



Mean 



value. 







111 

 111 



•7969 



Maximum 







•818 



Minimum 







111 



•778 





mine 









Differ 





•040 



Probable error 







•008 



In the course of the work the experiment of passing hydro- 

 gen sulphide over gently heated cadmium oxalate was tried. 

 This salt was completely transformed into the sulphide at a 

 temperature much below that, which is necessary for its con- 

 version into cadmium oxide. This reaction was then made the 

 basis of a new method for the determination of the atomic 

 weight of cadmium. The method used in the ten experi- 

 ments, the results of which are given below (Series III), was as 

 follows : 



Cadmium oxalate was placed in a porcelain boat and dried at 

 150° C. to a constant weight. It loses all of its moisture at 

 that temperature. While warm the boat was placed in the 

 weighing tube, allowed to cool and weighed. The boat con- 

 taining the cadmium oxalate was then placed in a tube arranged 

 for passing hydrogen sulphide and supported over a combus- 

 tion furnace as above described. The reducing gas was passed 

 through the tube and heat slowly applied. When the contents 

 of the boat had been completely changed to sulphide, the heat 

 was raised to incipient redness and kept at that temperature 

 for about one hour. The cadmium sulphide was allowed to 

 cool to about 200° C. in a slow stream of hydrogen sulphide 

 which was then displaced by a stream of pure dry carbon diox- 

 ide. While still warm the boat containing the cadmium sul- 



