on heating Mineral Substances, Meteorites, &c. 1 37 

 The following results were obtained : 



<() With strong sulphuric acid, carbon dioxide 



and sulphur dioxide 1-26 c.c. per gram. 



Hydrogen and trace of hydrocarbons 0*49 





Total 1-75 



Ferrous oxide 2*07 per cent. 



(6) With 50 per cent, sulphuric acid, carbon dioxide 0'23 

 Hydrogen and trace of hydrocarbons T64 



Total 1-87 



Ferrous oxide 2 '26 per cent. 



These figures indicate that the sulphur dioxide and hydrogen pro- 

 duced by the action of the strong acid is just equivalent to the hydro- 

 gen produced by the dilute acid, indicating that the felspar contains 

 metallic iron, which is probably the source of the whole of the hydro- 

 gen evolved when the mineral is treated with acid. The hydrogen and 

 carbon monoxide given off on heating the felspar are produced by the 

 action of water and carbon dioxide on ferrous oxide and metallic iron 

 present in the mineral. 



Both the gas obtained by heating the felspar and gases obtained 

 from the sealed tube experiments contained traces of hydrocarbon. This 

 may be accounted for on the assumption that the free iron in the felspar 

 contains a small quantity of carbide. 



Meteorites. 



It has long been known that considerable quantities of gas are 

 evolved when meteorites are heated in vacuo. The gas usually consists 

 of hydrogen, carbon monoxide, carbon dioxide, and hydrocarbons, in 

 varying proportions, and attempts have been made to draw conclusion 

 as to the origin of different meteorites from the results of analysis of 

 the gases obtained by heating them. These speculations are based 

 upon the supposition that the gases evolved on heating are present as 

 such in the meteorite, occluded from the atmosphere in which it pre- 

 viously existed. 



Beyond the gases already mentioned, the results of many observers 

 appear to show that nitrogen is also invariably present. Among those 

 that I have examined the gas evolved on heating contained, in no 

 single instance, a trace of nitrogen."* Grahamf found as much as 10 

 per cent, of nitrogen in the gas from the Lenarto meteorite, and 



* ' Koy. Soc. Proc.,' 1897, vol. 60, p. 442. 

 f ' Koy. Soc. Proc.,' 1867, vol. 15, p. 502. 



