26 



THE GASES IN ROCKS. 



TABLE 11. Stony meteorites. 



The figures for the Orgueil meteorite which yielded such a remarkable 

 amount of sulphur dioxide make the average for the sulphur gases an abnor- 

 mal one. The presence of this gas in quantity must mean that the meteor- 

 ite has suffered much from weathering and oxidation subsequent to its 

 fall. Considerable troilite has passed into iron sulphate which has been 

 decomposed by the heat of the combustion-furnace. 



Omitting the sulphur dioxide of this specimen, the average total volume 

 of gas from stony meteorites is reduced to 4.80 times the volume of the 

 meteoritic material. 



TABLE 12. Iron meteorites. 



1 Flight, Phil. Trans. No. 172 (1S82), pp. 893-894 and p. 896. 



Methane was determined in only two of these analyses. In these two 

 it averaged 0.10 volume; but in order to make the figures consistent in the 

 table, it was necessary to average these as if the eight other meteorites 

 yielded no marsh-gas, though it is highly probable that this gas was present 

 and has been included in the figures given for hydrogen. 



The unusual amount of gas from the Arva specimen recalls the be- 

 havior of the Toluca meteorite, 1 which, at the first attempt, produced 24.42 

 volumes of gas, owing to the presence of a small quantity of iron rust, but 

 whose pure metal evolved only 1.85 volumes. An average, omitting the 

 Arva, is therefore made. 



1 Ante, p. 22. 



