300 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 5-i 



TJrbain/ who purified his material by crystallizing thorium acetyl- 

 acetonate from solution in chloroform, gives the following analyses of the 

 anhydrous sulphate, effected by calcination: 



ThiSOt).. ThO.. Per cent. ThOi. 



1.0925 .6815 62.374 



.5926 .3699 62.420 



1.0230 .6384 62.405 



Mean, 62.400. ± .0096 



Hence Th = 233.75. 



Meyer and Guuiperz/ in order to determine whether thorium is com- 

 plex or not, prepared the octohydrated sulphate from material of diverse 

 origin, and analyzed it by dehydration and calcination. Their data, 

 which I give as one series, represent, first, six experiments upon prepara- 

 tions obtained by fractional precipitation as chromate; and, secondly, 

 six analyses of the sulphate prepared from three samples of thorium 

 chloride. I give here only the weights of the anhydrous sulphate and the 

 oxide, for the reason that the hydration of the compound was too irregu- 

 lar to yield good values for the atomic weight of thorium. 



.0024 



Hence Th = 232.45. From the uniformity of their results, Meyer and 

 Gumperz conclude that there is no evidence of a separation of thorium 

 into substances of different atomic weights. Their figures combine with 

 those of' previous investigations thus: 



Cleve 62.423. ± .0140 



Nilson 62.297, ± .0009 



Kruss and Nilson 62.297, ± .0013 



Urbain 62.400, ± .0096 



Meyer and Gumperz 62.288, ± .0024 



General mean 62.296, it .0007 



' Ann. Chim. Ph.vs. (7), 19, 223. 1900. 

 - Ber. Deutsch. chem. Ges., 38, 817. 190j. 



