15(5 THE ATOMIC WEIGHTS. 



CADMIUM. 



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

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

 oxygen.* With our value for the atomic weight of oxygen, these figures 

 make Cd ^ 110.64. This result has now only a historical interest. 



The more modern estimates of the atomic weight of cadmium begin 

 Avith the work of v. Hauer.f 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 gim. CdS. 69.209 per cent. 



6.6086 " 4-5746 " 69.222 " 



7-3821 " 5-i"7 " 69.245 " 



6.8377 " 4-7336 " 69.228 " 



8.1956 " 5-6736 " 69.227 " 



7-6039 " 5-2634 " 69.220 " 



7.T415 " 4-9431 " 69.217 " 



5.8245 " 4.0335 " 69.251 " 



6.8462 " 4-7415 " 69.257 " 



Mean, 69.231, zh .0042 



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. 63.9S2 per cent. 



.6552 " .4193 " 63.996 " 



.4017 . " .2573 " 64.053 " 



Mean, 64.010, ± .014 



Dumas II 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' weigh- 

 ings I calculate the ratio between CdCl.^ and 100 parts of silver: 



2.369 grm. CdClj = 2. 791 grm. Ag. 84.880 



4.540 " 5.348 " 84.892 



6.177 " 7.260 " 85.083 



2.404 " 2.841 " 84.618 



3-5325 " 4-166 " 84.794 



4.042 " 4.767 " 84.791 



Mean, 84.843, dr .026 



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

 + Journ. fiir Prakt. Chem., 72, 350. I857. 

 X Journ. fiir Prakt. Chera., 79, 281. i860. 

 II Ann. Chem. Pharm., 113, 27. iS6o. 



