ATOMIC WEIGHTS 



235 



CADMIUM. 



The earliest determination of the atomic weight of this metal was by 

 Stromeyer, who foimd that 100 parts of cadmium united with 14.352 of 

 oxygen.' Hence Cd = 111.483. This result has now only a liistorieal 

 interest. 



The more moclei'n estimates of the atomic weight of cadmium begin 

 with the work of v. Hauer." He heated pure anhydrous cadmium sul- 

 phate in a stream of dry hydrogen sulphide, and weighed the cadmium 

 sulphide thus obtained. His results were as follows, with the percent- 

 age of CdS in CdSO. therefrom deduced : 



7.7650 grm. CdSO^ gave .5.3741 grm. CdS. 



6.6086 " 4.5746 



7.3821 " 5.1117 



6.8377 " 4.7336 



8.1956 " 5.6736 



7.6039 " 5.2834 



7.1415 " 4.9431 



5.8245 " 4.0335 



6.8462 " 4.7415 



69.209 per cent. 



69.222 



69.245 



69.228 



69.227 



69.220 



69.217 



69.251 



69.257 



Mean, 69.231, -+z .0042 



Hence Cd = 111.935. 



Lenssen ^ worked upon pure cadmium oxalate, handling, however, 

 only small .quantities of material. This salt, upon ignition, leaves the 

 following percentages of oxide : 



.5128 grm. oxalate gave .3281 grm. CdO. 

 .6552 " .4193 



.4017 • " .2573 



63.982 per cent. 



63.996 



64.053 



Mean, 64.010, =t .014 



Hence Cd = 112.07. 



Dumas * dissolved pure cadmium in hydrochloric acid, evaporated the 

 solution to dryness, and fused the residue in hydrochloric acid gas. The 

 cadmium chloride thus obtained was dissolved in water and titrated with 

 a solution of silver after the usual manner. From Dumas' weighings 

 I calculate the ratio between CdCL and 100 parts of silver : 



1 See Berz. Lehrbuch, 5th Aufl., 3, 1219. 



2 Journ. prakt. Chem., 72, 350. 1S57. 

 3Journ. prakt. Chem., 79, 2S1. 1860. 

 ■•Ann. Chem. Phaim., 113, 27. 1S60. 



