THORIUM. 207 



The oxalate was subjected to a combustion analysis, whereby both 

 thoria and carbonic acid could be estimated. From the direct percentages 

 of these constituents no accurate value can be deduced, there having 

 undoubtedly been moisture in the material studied. From the ratio 

 between COg and ThOa, however, good results are attainable. This ratio 

 I put in a fourth column, making the thoria proportional to 100 parts of 

 carbon dioxide : 



Mean, 151. 114, i .053 



In 1882, Nilson's determinations appeared.* This chemist studied 

 both the anhydrous sulphate, and the salt with nine molecules of water, 

 using the usual calcination method, but guarding especially against the 

 hygroscopic character of the dry Th (SOJ2 and the calcined ThO.^. The 

 hydrated sulphate gave results as follows : 



Th{SO^^.gH^O. ThO.,. Percent. ThO.,. 



45.097 

 45-092 

 45.081 

 45.086 

 45.088 

 45-099 



Mean, 45.091, ± .0019 

 Delafontaine found, 45.062, zb .0332 



General mean, 45.090, ± .0019 



The anhydrous sulphate gave data as follows : 



.0009 



The last four determinations appear again in a paper published five 

 years later by Kriiss and Nilson,t who, however, give four more made 



*Ber. Deutsch. Chem. Gesell., 15, 2519. 1882. 

 tBer. Deutsch. Chein. Gesell., 20, 1665. 1887. 



