216 



THE ATOMIC WEIGHTS. 



A. 



52.83 



52.52 



52.72 



52.13 



52.47 ] 



52.49 



52.53 



52.13 



52.13 



52.43 



52.60 



52.40 

 52.96 

 52.82 J 



Mean, 52.511, d 



Hence ThO^ = 266.025, ± .363. 



.047 



In three experiments with this lower hydrate the sul- 

 phuric acid was also estimated, being thrown down as 

 barium sulphate after removal of the thoria : 



The figures in parenthesis are reproduced by myself from 

 Delafontaine's results, he having calculated his analyses with 

 O = 100, S = 200, and Ba = 857. These data may be re- 

 duced to a common standard, so as to represent the quantity 

 of 2Th(SO,),.9H20 equivalent to 100 parts of BaSO^. We 

 then have the following results : 



106.597 

 106.704 

 109.226 



Mean, 107.509, zh .585 



Hence ThO, = 259.555, =b 2.725. 



Delafontaine seems himself to have calculated from the 

 ratio between the percentages of SO 3 and ThOa ; whence, 

 with our revised values for S, Ba, and 0, ThO^ = 262.643. 



Delafontaine's work was soon confirmed by Hermann,* 



* Journ. fiir Prakt. Chem., 93, 114. 



