THORIUM. 



205 



We may fairly assume that these figures were calculated with = 8, 

 C = 6, and S = 16. Correcting by the values for these elements which 

 have been found in previous chapters, Th0 2 becomes as follows : 



From sulphate ThO 2 = 267.170, rfc .7950 



From acetate " = 267.488, .7950 



From formate " = 271.239, .8698 



From oxalate " = 261.478, d= .4884 



General mean ............. ThO 2 = 265.103, -3394 



The single result from the double potassium sulphate is included with 

 the column from the ordinary sulphate, and the influence of the atomic 

 weight of potassium is ignored. 



Chydenius was soon followed by Marc Delafontaine, whose researches 

 appeared in 1863.* This chemist especially studied thorium sulphate ; 

 partly in its most hydrous form, partly as thrown down by boiling. In 

 Th(S0 4 ) 2 .9H 2 0, the following percentages of Th0 2 were found : 



45.08 

 44.90 

 45.06 



45- 21 

 45.06 



Mean, 45.062, dz .0332 



The lower hydrate, 2Th(SO 4 ) 2 .9H 2 0, was more thoroughly investi- 

 gated. The thoria was estimated in two ways : First (A), by precipita- 

 tion as oxalate and subsequent ignition ; second (B), by direct calcination. 

 These percentages of Th0 2 were found : 



52.83! 



52.72 



52.I3J 



52.47 



52.49 



52.53 



52-13 



52.13 



52.43 



52.60 



52.40 



52.96 



52.82 



Mean, 52.511, .047 



In three experiments with this lower hydrate the sulphuric acid was 

 also estimated, being thrown down as barium sulphate after removal of 

 the thoria : 



*Arch. Sci. Phys. et Nat. (2), 18, 343. 



