396 SMITHSOXIAX MISCELLANEOUS COLLECTIONS VOL. 54 



In 1861 new determinations were publislied by Chydenins,' whose 

 memoir is accessible to me only in an abstract "" which gives results with- 

 out details. Thoria is regarded as a monoxide, ThO, and the old equiv- 

 alents (0 = 8) are used. The following values are assigned for the 

 molecular weight of ThO, as found from analyses of several salts: 



Mean, 67.252, ± .201 



Mean, 65.85, ± .123 



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, ThOo becomes as follows: 



From sulphate ThO^ = 269.18 



From acetate " = 269.46 



From formate " =: 273.25 



From oxalate " = 263.42 



Average ... Tli02 = 268.83 



And Th = 236.83. 



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 es|3ccially studied thorium sulphate; 

 partly in its most hydrous form, partly as thrown do^m by boiling. In 

 Th(S04)2.9H20, the following percentages of ThO. were found: 



* Kemisk undersSkning at Thorjord och Thorsalter. Helsingfors, 1861. An academic disser- 

 tation. 

 ^Poggend. Annal., 119, 55. 1863. 

 »Arch. Sci. Phys. Nat. (2), 18, 343. 



