TRANSACTIONS OF SECTION B. 



609 



3. On tlui Chemistry and the Atomic Weight of Thorium, 

 By Professor Bohuslav Brauner, Prague. 



The author finds that the reaction -which forms the basis of the separation of 

 thorium from other Bare Earth Metals, is due to the formation of a new complex 

 salt containing for one molecule of thorium oxalate, two molecules of ammonium 

 oxalate, and four or seven molecules of water. The salt is decomposed by -water, 

 but it can be kept in solution by the presence of one additional molecule of 

 ammonium oxalate. He shows ho-w this behaviour may be used for the prepar- 

 ation of pure thorium salts. The thorium oxalate prepared in this -way was 

 analysed by determining the ratio of thorium oxide to oxalic acid (by means of 

 permanganate), and the number 232-5 (0 = 16) -was obtained. The author shows 

 that Meve's number, Th = 234-5, is too high, the oxalate being easily decomposed 

 (basic salt is formed) by the action of hot water. 



4. The Atomic Weights of Nickel and Cobalt} By Professor Theodore 

 W. Richards, A. S. Cushman, and G. P. Baxter. 



Four samples of the pure bromide of each metal -were made and analysed. Two 

 of the nickel preparations were freed from cobalt by ordinary processes, and two 

 were purified by Mond's process. Fractional crystallisation of the ammonia- 

 bromide was adopted as a means of further purification, after all known impuri- 

 ties had been removed ; and the fourth sample of nickel was also precipitated 

 fractionally by electrolysis. Each specimen was precipitated as hydroxide from 

 the ammonia-bromide by boiling its aqueous solution in a platinum dish, thus 

 insuring the absence of alkalies and silica. The hydroxide was ignited, the oxide 

 reduced, and the bromide formed by the action of bromine vapour at a red heat. 

 Sample I. was the least carefully treated. Sample IV. the most. 



In the case of the cobalt, similar precautions were taken. The first sample 

 was purified by fractional precipitation as the double nitrite with potassium ; the 

 second sample by successive conversions into a cobaltamine compound ; the third 

 by a combination of both of these methods ; and the fourth by the resublimation 

 of the third specimen. 



All the samples of both bromides were sublimed as anhydrous crystals in a 

 stream of hydrobromic acid gas ; the specific gravity of the nickel salt was found 

 to be 4-64, and that of the cobalt salt 4-91. The bromides were ignited, bottled, 

 and weighed by means of the Hichards-Parker drying apparatus ; - and having 

 been dissolved in water, they were decomposed by argentic nitrate. In the later 

 analyses, the weight of the silver taken, as well as of the argentic bromide 

 obtained, was determined. 



1897. 



Atomic Weight oj" Nickel. 



' Am. Acad. Proc, xxxiii. pp. 95-128. 

 ' Am. Acad. Proc, xxxii. p. 59. 



R R 



