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



Mallett* found 10 per cent, of nitrogen in the gas from a meteorite 

 from Augusta Co., Virginia. Wrightf examined a large number of 

 meteorites, and found that in almost every case the gas contained 

 nitrogen. In this case, however, the presence of nitrogen can easily 

 be accounted for, as no particular precautions were taken with regard 

 to the thorough exhaustion of the apparatus employed. A Sprengel 

 pump was used, " which was kept running till the air was thoroughly 

 removed, as could be seen ~by the gauge" DewarJ found nitrogen, in 

 quantities not exceeding 4 per cent, of the total gas, in the gases from 

 samples of meteorites and graphite. 



In one single case a meteorite has been found to yield a trace of 

 helium on heating. 



With regard to the carbon dioxide and combustible gases, it is diffi- 

 cult to obtain direct evidence as to their origin. In the case of 

 meteorites containing bituminous matter and carbonaceous nodules, the 

 evolution of these gases may be attributed to the destructive distilla- 

 tion of their constituents. Meteorites of the stony variety appear to 

 evolve more carbon dioxide and hydrocarbons, and less hydrogen and 

 carbon monoxide, than those which are of a metallic nature. Several 

 specimens of stony meteorites have been carefully examined by Wright 

 and Dewar with the following results : 



Wright (loc. cit.) found that in the case of a stony meteorite from 

 Iowa Co., Iowa, the carbon dioxide was given off at a very low tem- 

 perature. The following table shows 'the composition of the gas given 

 off at different temperatures : 



The meteorite lost about 10 per cent, of its weight of water on 

 heating. The water was allowed to collect in the apparatus, and as no 

 drying reagent was used, it is easy to account for the presence of 

 hydrogen in the gas. The carbon dioxide may have been present as 

 an unstable hydrated carbonate, or in the state of occlusion in the 

 pores of the substance. 



Dewar (loc. cit.) showed that a meteorite of a similar nature was 

 capable of reabsorbing water and carbon dioxide after the gases had 

 been removed by heating in vacuo. The following results were 

 obtained : 



* ' Roy. Soc. Proc.,' 1872, vol. 20, p. 365. 



f ' Amer. J. Sci.,' [3], vol. 9, pp. 294 and 459; vol. 10, p. 44; vol. 11, p. 254. 



J ' Roy. Inst. Proc.,' 1886, p. 545. 



' Nature,' 1896. 



