1886.J 



On the Gaseous Constituents of Meteorites. 



553 



It will be seen that the above numbers are quite confirmatory of 

 Wright's results, the carbonic acid in the three meteorites examined 

 being by far the largest constituent, while marsh- gas in considerable 

 quantity was found in all. The percentage of this latter gas is some- 

 what higher than that found by Wright in the stony meteorites he 

 examined, but this is probably due to the fact that a rather higher 

 temperature was employed by us to drive off the gases. This 

 supposition seems to be confirmed on considering the analysis of 

 the Pultusk meteorite, which is the only one examined both by 

 Wright and ourselves ; for whereas his abstracted gas only reached 

 1"75 times the volume of the stone, the total quantity of gas obtained 

 by us was twice as much or equal to 3 '54 times its volume. 



It is therefore unquestionable that marsh-gas is given off on heating 

 these meteoric stones, but whether it exists as such occluded in the 

 material, or whether it is formed by some chemical decomposition of 

 some organic constituent of the mass is by no means clear. 



Wright came to the conclusion "that the marsh-gas really existed 

 as such in the stony meteorites, as the temperature at which it was 

 driven off would be too low for its formation," at the same time he 

 thinks it quite possible that " at very much higher temperatures, in 

 the reaction by which the carbonic acid is broken up by the iron, a 

 portion of the carbon might combine with the hydrogen present to 

 form marsh-gas." 



We shall return to this question of the formation of marsh-gas, after 

 we nave described the experiments in the various forms of graphite. 



Knowing the great absorptive power for gases possessed by porous 

 bodies generally, it was thought advisable to determine directly what 

 this absorptive power was in the case of these stony meteorites, 

 which are of such an eminently porous nature. 



For this purpose the powdered Dhurmsala meteorite, from which 

 the gases had been removed, was left in moist air under a bell glass, 

 for different periods of time as tabulated below, the gases being drawn 

 off at a low red heat after each period : — 





Occluded gas in 











/ 



vols, of the 













meteorite. 



C0 2 . 



CO. 



H. 



N. 





. . 0-61 



54-0 





42-4 



3-6 



After 6 days more . . 



. . 2-47 



47-0 



5-0 



47-0 



1-0 



After 8 days more . . 



. . 0-63 



96-1 



2-0 



1-5 





The absorption of water and gases evidently went on tolerably 

 rapidly for the first seven days, but after the second heating of the 

 meteorite, its porosity seems to have been affected in some way, for 

 after a further period of eight days, we find it taking up only about a 

 fourth of the quantity of gas which it had absorbed in the previous 

 six days. 



