542 Professor Dewar [June 11, 



of gas extracted was mucli greater in tlie case of the stony meteorites 

 than in the iron ones, the principal characteristics of these gases 

 being, that in the former the carbonic acid greatly predominated, 

 accompanied by a comparatively small amount of carbonic oxide and 

 hydrogen, whereas in the latter the carbonic acid never exceeded 

 20 per cent., the carbonic oxide being, as a rule, considerably more 

 than this, and the hydrogen sometimes reaching as high as 80 per 

 cent. 



It is impossible, however, to arrive at anything more than general 

 conclusions as to the total amount of gas given off by any special 

 meteorite, or its composition, for, as shown by Wright and confirmed 

 by Mr. Ansdell and the lecturer, both the total quantity and com- 

 position of the gases vary very considerably according to the tem- 

 perature at which they are drawn off. 



Wright found a notable quantity of marsh-gas in all the stony 

 meteorites which he examined, though not a trace in any of the iron 

 ones; this seemed to be a distinctive difference between the two 

 classes of meteorites, but subsequently Dr. Flight, of the British 

 Museum (Phil. Trans, vol. clxxiii. (1882) p. 885), found marsh-gas 

 in a specimen of the Cranbourne siderite, so that it is evident certain 

 of the iron meteorites also contain this gas. 



Lawrence Smith (Amer. Journ. 1876) confined himself princi- 

 pally to an examination of the graphite nodules which are frequently 

 found imbedded in the iron meteorites, and to the nature of the carbon 

 in the so-called carbonaceous meteorites. He extracted the organic 

 or hydrocarbon-like bodies by means of ether, but did not determine 

 the gases given off on heating. Previous to this, Eoscoe (Pro. Phil. 

 Soc. Man. 1862) had obtained the same hydrocarbon-like body by 

 exhausting the Alais meteorite with ether, but the quantity he had to 

 work upon was so small that he could not make a very complete 

 examination. 



These are some of the principal points that have been made out 

 with regard to the gases occluded by meteorites. The results, 

 however, are so comparatively few, that it was thought worth while to 

 take the opportunity which presented itself, of having several good 

 specimens of meteorites to confirm these results, and, if possible, add 

 something to our present knowledge of the subject. 



The investigation may be divided into five parts, having the 

 following objects in view : firstly, the confirmation of previous 

 results by the examination of some well-known meteorite ; secondly, 

 the analysis of several whole meteoric stones, whose interior had 

 never been exposed to the effects of the atmosphere, by reason of the 

 characteristic coating of glaze ; thirdly, the examination of a celestial 

 graphite nodule, taken from the interior of an iron meteorite; 

 fourthly, the comparison of some meteorite of the carbonaceous class 

 with the above ; and fifthly, the examination of different terrestrial 

 graphites. 



The method employed for the abstraction of the gases was exactly 



