evolved on heating Mineral Substances, Meteorites, fyc. 141 



A series of experiments were undertaken to determine the conditions 

 under which the minerals gave off helium. It was found that from 

 deveite helium was evolved, but very slowly, at the temperature of 

 boiling quinoline, and somewhat faster at the temperature of boiling 

 sulphur. At a bright red heat a considerable quantity of helium 

 was obtained, but in no case did the mineral lose the whole of its 

 helium under the influence of heat alone. 



By heating cleveite to redness for some hours a mixture of helium, 

 hydrogen, carbon dioxide, and carbon monoxide was obtained; the 

 gas came off readily at first, and appeared finally to cease altogether. 



A quantity of the same sample was completely decomposed by 

 means of sulphuric acid (30 per cent.) in an exhausted sealed tube. 

 The results are given below : 



By heating the mineral. By action of sulphuric acid. 



He 1-487 c.c. per gram. 3-201 per cent, per gram. 



H. 2 0-367 0-333 



C0 2 2-298 



It will be noticed that only half the helium is given off on heating 

 the mineral; this makes it appear probable that if the helium is 

 present in the mineral originally in a state of binary combination the 

 decomposition takes place according to the equuation : 



XHe 2 = XHe + He. 



A specimen of fergusonite was also examined, but the results were not 

 altogether satisfactory, as it was found to be practically impossible to 

 completely decompose the mineral by the action of 30 per cent, sulph- 

 uric acid; strong sulphuric acid appeared to be still more inactive. 

 When fused with acid potassium sulphate a larger yield of helium was 

 obtained but the mineral was not completely decomposed. The follow- 

 ing figures indicate that about half the helium contained in the mineral 

 is liberated under the influence of heat. 



By action of heat on By 30 per cent. Fusion with acid 



mineral. sulphuric acid sulphate. 



He ... 1-041 c.c. per gram. 1*434 c.c. per gram. 1-813 c.c. per gram. 

 H 2 ... 0-231 0-163 



CO, &c. 0-326 



It is somewhat significant that both cleveite and fergusonite yield 

 hydrogen when decomposed by sulphuric acid. If the helium were 

 present in combination with a metal it would eventually be liberated 

 as a hydride. It is probable that the hydride would be a very unstable 

 compound and would decompose at the moment of formation. Part of 

 the hydrogen would probably be taken up by the ferric and uranic 

 compounds, and part would escape in the gaseous state. A similar 



