506 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5-i 



one conversion of the sulphide into oxide. The figures are, however, 

 not valuable enough to cite. 



The foregoing data involve one variation frf»in Beringer's paper. 

 Where I put CcOn as found he puts Ce.O.. The latter is plainly inad- 

 missible, although the atomic weiglits calculated from it agree curiously 

 well with some other determinations. Obviously, the presence of didym- 

 ium in the salts analyzed tends to raise the apparent atomic weight of 

 cerium. 



Shortly after Beringer, Hermann ' published the results of one experi- 

 ment. 23.532 grm. of anhydrous cerium sulphate gave 29.160 grm. of 

 BaS04. Hence 100 parts of the sulphate correspond to 123.926 of BaSO^, 

 and Ce = 138.44. 



In 1848 similar figures were published by Marignac," who found the 

 following amounts of BaSO^ proportional to 100 of dry cerium sulphate: 



122.68 

 122.00 

 122.51 



Mean, 122.40, ± .138 



Hence Ce = 141.97. 



If we give Hermann's single result the weight of one experiment in 

 this series, and combine, we get a mean value of 122. 856, ±.130. 



Still another method was employed by Marignac. A definite mixture 

 was made of solutions of cerium sulphate and barium chloride. To this 

 were added, volumetrically, solutions of each salt successively, until 

 equilibrium was attained. The figures published give maxima and 

 minima for the BaCL proportional to each lot of Ceo( 804)3. Tn another 

 column, using the mean value for BaCl, in each case, I put the ratio 

 between 100 parts of this salt and the equivalent quantity of sulphate. 

 The latter compound was several times recrystallized : 



Ce.iSOi),. BaGl^. Ratio. 



First crystallization... 11.011 11.990 — 12.050 91.606 



First crystallization... 13.194 14.365 — 14.425 91.657 



Second crystallization. 13.961 15.225 — 15.285 91.518 



Second crystallization. 12.627 13.761 — 13.821 91.559 



Second crystallization. 11.915 12.970 — 13.030 91.654 



Third crystallization... 14.888 16.223 — 16.283 91.602 



Third crystallization... 14.113 15.383 — 15.423 91.755 



Fourth crystallization. 13.111 14.270 — 14.330 91.685 



Fourth crystallization. 13.970 15.223 — 15.283 91.588 



Mean, 91.625, ± .016 



Hence Ce = 141.33. 



^ Journ. prakt. Chem., 30, 185. 1843. 



2 Arch. Sci. Phys. Nat. (1), 8, 273. 1848. OeuvTes Complies, 1, 215. 



