134 Dr. M. W. Travers. The Origin of the Gases 



CO., .................. 13-38 c.c. per gram. 



H,,~&c ................ 0-25 



The greater part of the hydrogen and hydrocarbons is probably pro- 

 duced by the breaking down of organic matter in the mineral. This 

 organic matter may be due to infiltration from the surface, but, con- 

 sidering the treatment the mineral had received, it is more probably 

 contained in the foraminiferous casts, the decomposition products of 

 their original occupants. 



The presence of manganous oxide in minerals appears also to favour 

 the production of hydrogen and carbon dioxide ; indeed, it has long 

 been known, that when moist manganous carbonate is heated, these 

 gases are always produced along with carbon dioxide. 



The first reactions which take place when the mineral is heated, may 

 be expressed by the equations : 



MnO + H.,0 = MnO., + H, 

 MnO + CO = MaO 



But it was found that when cerite, a mineral which contains a consider- 

 able quantity of manganous carbonate was heated, the gas contained 

 not only hydrogen, but oxygen, the product of a reaction taking place 

 at a somewhat higher temperature : 



3Mn0 2 = Mn 3 4 + 0,. 



Analysis of the gas obtained by heating finely powdered cerite gave 

 the following results : 



CO., ............ 15'0 (about) c.c. per gram. 



CO" ............ 1-554 



H., ............ 3-905 



O; ............ 0-406 



A cobalt ore containing only the higher oxides of manganese gave 

 about 10 c.c. of oxygen per gram of minerals.* 



Yttrotantalite, samarskite, &c., containing lower oxides of uranium, 

 also give small quantities of hydrogen when heated. The hydrogen 

 may be produced according to the equation : 



The quantity of hydrogen is not, however, very large. 



Minerals containing sulphides usually give a mixture of hydrogen, 

 sulphuretted hydrogen, and sulphur vapour when heated. The quantity 

 of gas is often very large, but the reaction is too complicated for direct 

 investigation. It is probable that the sulphides react with water 



* ' Roy. Soc. Proc.,' TO!. 60, p. 444. 



