CADMIUM. 161 



Bucher's next series of deternnnations was by Partridge's method — 

 the conversion of cadmium oxahite into cadmium sulphide by heating 

 in a stream of sulphuretted hydrogen. The sulphide was finally cooled 

 in a current of dr}^ nitrogen. The vacuum weights and ratios are sub- 

 joined : 



Oxalate. Sulphide. Percentage. 



2.56319 1.S4716 72.065 



2.18364 I. 57341 72.055 



2. 1 1643 1.52462 72.037 



3.13105 2.25582 72.047 



Mean, 72.051, ± .0127 

 Partridge found, 71.973, =t .0007 



General mean, 71.974, dr .0007 



Here Bucher's mean practicall}^ vanishes. 



The third method employed by Bucherwas that of weighing cadmium 

 chloride, dissolving in water, precipitating with silver nitrate, and weigh- 

 ing the silver chloride found. The cadmium chloride was prepared, 

 partly by solution of cadmium in hydrochloric acid, evaporation to 

 dr3mess, and sublimation in vacuo; and partly by the direct union of 

 the metal with chlorine. The silver chloride was weighed in a Gooch 

 crucible, with platinum sponge in place of the asbestos. To the vacuum 

 weights I append the ratio 2AgCl : CdCl.^ : : 100 : x. 



CdCl,. 

 3.09183 

 2.26100 



1-35729 



2.05582 



1-89774 

 3-50367 

 2.70292 

 4.24276 

 3.40200 

 4.60659 

 2.40832 

 2.19144 

 2.84628 

 2.56748 

 2.31003 

 1.25008 

 I. 96015 

 2.29787 

 1.94227 

 I. 10976 

 1 . 63080 



Mean, 63.916, zb .0032 



Bucher gives a rather full discussion of the presumable errors in this 

 method, which, however, he regards as somewhat compensatory. The 

 11 



