ATOMIC WEIGHTS 337 



and the oxide so produced was finally ignited and weighed. Their data, 



with vaciuim weights, are as follows : 



CbCh. GKO^. Per cent. Cb^O,. 



9.56379 4.71539 49.305 



5.42742 2.65730 49.292 



5.15992 2.54364 49.296 



9.64854 4.7564] 49.297 



7.24572 8.57222 49.301 



8.00559 3.94746 49.309 



9.60763 4.73852 49.324 



9.19732 4.53638 49.323 



4.27456 2.10734 49.300 



Mean, 49.305, ± .0026 



Hence, if 01 = 35.4584, Cb = 93.538. It is not necessary to combine 

 this value with the earlier determinations, for the reason that it sup- 

 plants them. It is, however, near one of Marignac's values, which has 

 confirmatory significance. The atomic weight of columbium appears to 

 be quite near 93.5. The results obtained by Deville and Troost ' for the 

 vapor densities of columbium chloride and oxychloride are in harmony 

 with this conclusion. ^ 



TANTALUM. 



The results obtained for the atomic weight of this metal by Berzelius,"^ 

 Rose,^ and Hermann * may be fairly left out of account as valueless. 

 These chemists could not have worked with pure preparations, and their 

 data are sufficiently summed up in Becker's " Digest." 



Blomstrand's determinations,^ as in the case of columbium, were made 

 upon the pentachloride. His weights are as follows : 



1 Compt. Rend., 56, 891. 1863. 

 - Poggend. Annalen, 4, 14. 1825. 

 spoggend. Annalen, 99, 80. 1856. 

 ^Joum. prakt. Chem., 70, 193. 1S57. 

 5 Acta Univ. Lund, 1864. 



