DISTRIBUTION OF ORGANIC SUBSTANCES 123 



cent higher than that in terrestrial carbonates and 1-3 per 

 cent lower than that in biological objects. ^^ There is reason 

 to suppose that it approximates very closely to the original 

 isotopic composition of carbon on the surface of Earth and 

 that the divergence of the proportions of the isotopes of 

 carbon did not arise until the period in the history of our 

 planet when life had developed and biological processes were 

 taking place. 



The forms in which carbon is commonly found on meteor- 

 ites are carbides and native carbon, either in the amorphous 

 state, or as graphite or diamonds. Graphite, in particular, 

 has been found in iron meteorites in the form of nodules, 

 flakes and granules which sometimes attain a weight of 1 2 g. 

 Erofeev and Lachinov were able to isolate about 1 per cent 

 of carbon in the form of diamond from the meteorites which 

 fell near the village of Novo-Urei in the province of Penza 

 in 1887. Later A. E. Foote and Koenig obtained diamond 

 dust from the meteorites which fell in the Diablo canyon in 

 Arizona. Weinschenk also found diamonds in the Magura 

 meteorites.*^ 



Weinschenk was also the first to find cohenite, a mineral 

 which is very widely distributed in and characteristic of 

 meteorites. It is a carbide of iron, nickel and cobalt and has 

 the general formula (Fe, ni, 00)30. 



Cohenite is the parent substance of the free carbon and of 

 the hydrocarbons which have been found in a number of 

 meteorites. 



As early as 1857 F. Wohler^-^ succeeded in isolating a 

 certain amount of organic material similar to ozocerite from 

 the stony meteorite which fell near Kaba in Hungary. Analy- 

 sis of this material showed definitely that it was composed 

 of hydrocarbons of high molecular weight. A similar ma- 

 terial was isolated from the meteorite which fell in Cold 

 Bokkeveld in Cape Province. This meteorite contained up 

 to 025 per cent of hydrocarbons. P. Melikov and V. Krshiz- 

 hanovskii*^ found a small amount of hydrocarbons in the 

 silicate meteorite which fell in the village of Migeya near 

 Elizavetgrad in the Khersonese in 1889. In his book von 

 Kliiber^* gives a general account of the occasions on which 

 hydrocarbons have been found in meteorites. In particular. 



