1886.] On the Gaseous Constituents of Meteorites. 555 



associated. These rocks are very variable, but consist principally of a 

 kind of decomposed trap or gneiss. We succeeded in obtaining a good 

 specimen of semi-decomposed gneiss from Canada with a consider- 

 able quantity of graphite disseminated throughout the mass, and also' 

 several samples of Ceylon graphite imbedded in its matrix, which in 

 this case consisted of felspar and quartz. 



The results, as tabulated below, confirm Wright's analyses of 

 several trap rocks, in which he found principally carbonic acid and 

 hydrogen. The small quantity of marsh-gas no doubt comes from 

 the disseminated graphite, but the presence of the hydrogen is more 

 difficult to explain and requires further investigation. 





Sp. gr. 



Occluded 

 gases in 

 vols, of the 

 graphite. 



C0 2 . 



CO. 



H. 



CH 4 . 



% 



Celestial graphite 



2-26 



7 25 



91 -81 





2-50 



5-40 



o-i 



Borrodale „ 



2-86 



2-60 



36 -40 



7-77 



22-2 



26-11 



6 66 



Siberian „ 



205 



2-55 



57 -41 



6 16 



10-25 



20-83 



416 



Ceylon „ 



2'25 



0-22 



66-60 



14-80 



7-40 



3-70 



4-50 



Unknown „ 



1-64 



7-26 



50-79 



3 16 



2-50 



39-53 



3-49 





2 45 



5 32 



82 -38 



2-38 



13-61 



0-47 



1-20 





2-59 



1-27 



94-72 



0-81 



2-21 



0-61 



1-40 



On comparing these samples of graphite, it will be seen that the 

 Borrodale and the Siberian give off about the same total volume of 

 gas, that the celestial and the unknown graphites closely approximate 

 each other in this respect, yielding more than double the volume of 

 the others, and that the Ceylon sample stands alone in yielding a very 

 minute quantity. All the terrestrial samples, except that from Ceylon, 

 are alike in giving off a very considerable quantity of marsh-gas, 

 though they differ somewhat in the actual quantity, and it is evident 

 that, although the celestial graphite contains a considerable amount,, 

 it is very much less than that yielded by the terrestrial samples. 



A few tentative experiments were made to ascertain the absorbing 

 power for gases of this celestial graphite. For this purpose dry car- 

 bonic acid, marsh-gas, and hydrogen were respectively drawn through 

 the tube containing the previously exhausted graphite for twelve- 

 hours in the cold, the gases being pumped out at a low red heat after 

 each treatment with the dry gas. After the carbonic acid treatment 

 the volume of gas collected was only 1*1 times that of the graphite,, 

 containing 98'4 per cent, of carbonic acid ; after the marsh-gas the 

 volume of the gas was only - 9 that of the graphite, containing 94*1 

 per cent, carbonic acid ; and after the hydrogen the volume of the gas 



