402 STUDIES FOR STUDENTS 



of gas, consisting of hydrogen in preponderance, carbon dioxide, 

 and carbon monoxide in large percentage, and nitrogen and 

 marsh gas in small quantities, with water vapor, but with a prac- 

 tical absence of oxygen. Twenty-five analyses including ancient 

 and modern volcanic and even some metamorphic rocks gave an 

 average volume of gas equal to about four and one half times 

 the volumes of the containing rocks."' Further, it is urged that 

 no meteorites have been analyzed as to their gases immediately 

 after their fall. In contrast to these facts it should be noted 

 that the Homestead meteorite was analyzed for gases by Wright 

 within three months from the time of its fall. A second analy- 

 sis was made a year later in order to test the influence of the 

 earth's atmosphere upon the stone. It was found that very little 

 change had taken place except a slight loss of carbonic acid. 

 Ansdell and Dewar in testing the gases of the Pultusk and Mocs 

 meteorites chose stones of those falls which were completel}' 

 incrusted so that the chances of absorption of gases from the 

 earth's atmosphere might be reduced to a minimum. Yet the 

 results obtained accorded well with those from other meteoric 

 stones and for Pultusk the percentages were remarkably like 

 those derived by Wright in a previous and independent examina- 

 tion of stones of the same fall. There seems, therefore, good 

 reason to believe that the gases obtained from meteorites are 

 brought with them from space and that they have not been 

 derived from the earth's atmosphere. 



How the gases are held by the meteorites is uncertain. 

 Wright was inclined to believe that the pores occasionally noted 

 in the silicates of meteorites indicated cavities where the gas 

 was held. Such pores are of too rare occurrence, however, to 

 meet the demands of the problem. The phenomenon seems 

 more like the occlusion of hydrogen by platinum or zinc, and 

 the gases are probably held partly in the intermolecular spaces 

 and partly chemically united. Travers, however, regards them 

 as produced by heat from the non-gaseous elements of the 



■T. C. Chamberlin : Jour. Geol., Vol. VII, p. 558. Quoted from Chemical 

 News, April 9, 1897. 



