120 Journal of the Mitchell Society. [Dec. 



radio activity of which was discovered by G. C. 

 Schmidt and Mme. Curie. The question, whether 

 thorium is primarily radio active or whether its 

 activity is due to the admixture of other radio active 

 substances, is treated. The work carried out by 

 Rutherford and his co-laborers on this subject is 

 briefly stated. While these investigations were^made 

 with commercial thorium without regard to its source, 

 Hofmann and Zerban paid strict attention to the 

 latter. From observations made with thorium from 

 all the important thorium minerals the conclusion is 

 drawn that thorium itself possesses no primary radio 

 activity. 



16. Thorium, Carolinium and Berzelium: 



Chas. Baskerville. 



This paper presents a brief historical account of the 

 discovery of thorium and the questions raised as to 

 its elementar}' character. The published evidence is 

 considered in conjunction with experimental data 

 obtained, and the conclusions arrived at that 

 thorium is not a primary radio active body. The 

 complex nature of thorium is proved by the conduct 

 of salts with certain organic bases, as phenylhy- 

 drazine, for example. Fractions were added giving 

 atomic weights from 212 to 252, the original being 

 232.5. Pure thorium oxide from several sources was 

 converted into the chloride by heating it, mixed with 

 pure sugar carbon within quart tubes, during the 

 passage of dry chlorine. A volatile chloride, "weisser 

 dampff" of Berzelius, was obtained, decreasing in 

 amount according to the duration and temperature of 

 the reaction. The purified, delicately green oxide 

 obtained from this gave a specific gravity of 8.47 and 

 the element berezelium an atomic weight of 212 

 (tetrad). The temperature of the tube was raised 

 and thorium tetrachloride distilled away. The 

 residue in the carbon boat on purification gave a 

 greyish pink oxide with a specific gravity of 11.26 

 and an atomic weight of (tetrad) 255.6 (carolinium). 

 The new thorium, or that in a large measure freed 

 from the berezelium and carolinium, gave an atomic 

 weight of 220.6, and a white oxide with a specific 



