28 Field Columbian Museum — Geology, Vol. i. 



and containing carbon compounds closely resembling terrestrial bitu- 

 mens. Notably in the Cold Bokkeveld meteorite (246) occurs a sub- 

 stance much like bitumen from which a wax-like hydrocarbon can be 

 dissolved out by alcohol. Other examples of carbonaceous meteorites, 

 are those of Alais (221), Orgueil (282), Entre Rios (320), and Kaba. 



As these carbon compounds seem to exist only in the pores of the 

 stone, it has been suggested by Maskelyne that they may have been 

 absorbed during its passage through the atmosphere, but this is not 

 certain. Besides the carbon compounds, some meteorites of this class 

 contain soluble alkaline salts which act as a cement to consolidate the 

 meteorite, but when moistened with water cause it to completely dis- 

 integrate. These salts are sulphates of sodium, calcium, magnesium 

 and potassium. 



Having thus traced in outline the principal characters of meteor- 

 ites there remains for answer the interesting question as to what has 

 been the probable origin of these bodies. While it is not the prov- 

 ince of this Handbook to enter into any elaborate discussion of the 

 question, a study of meteorites can hardly be considered complete 

 without a mention of some of the different theories which have been 

 proposed to account for their origin. 



It is evident, as has been said, from the chemical character of 

 the substances found in meteorites, that water and air must have 

 been absent from the laboratory of nature in which they were formed. 



It is apparently true also that life had nothing to do with the 

 formation of the substances which meteorites contain. The consti- 

 tuent substances most likely to have been of organic origin are the 

 hydro-carbons previously mentioned, which resemble terrestrial bitu- 

 mens. The latter are generally regarded as being one of the products 

 of the decomposition of vegetable matter, but that they may have had 

 a mineral origin as well is not denied, so that the presence of similar 

 substances in meteorites is no proof of previous life. 



The close resemblance which aerolites bear to volcanic terres- 

 trial rocks has led many to seek their origin in material ejected 

 from the volcanoes of the earth or moon. 



This view has had many able supporters, notably the astronomer 

 Laplace and the mineralogist J. Lawrence Smith. A careful study 

 however of the amount of projectile force required to throw the me- 

 teoric bodies beyond the attraction of the terrestrial or lunar sphere 

 and of the amount of matter which must have been thus ejected in 

 order to furnish the number of meteorites that have been observed, 

 shows both to be far beyond any probable quantity. 



