THE CONSTITUENTS OF METEORITES 529 



terrestrial hydrocarbons need not always be referred to an 

 organic origin, but may have been formed in a purely inorganic 

 way. 



The occurrence of hydrocarbons in meteorites further shows 

 that such meteorites could not have been subjected to any 

 high degree of heat subsequent at least to the formation of these 

 compounds, and that the heating of meteorites during their fall 

 to the earth has in many cases been only superficial. 



The trails of light, sometimes enduring several minutes, 

 observed following in the wake of some meteors may perhaps 

 indicate the presence of carbonaceous matter in those bodies. 

 The stone shower which took place at Hessle was accompanied 

 by luminous effects and with the stones fell a brownish-black 

 powder which contained 71 per cent, carbonaceous matter. 

 Other carbonaceous meteorites have fallen, however, without 

 exhibiting any marked luminous phenomena. 



Other compounds. — Besides the above well-determined com- 

 pounds a number of others have been reported at different times 

 which are (i) present in insignificant amount or (2) their 

 occurrence has not been confirmed, or (3) they may be of ter- 

 restrial origin. Among these a few may be mentioned : Quartz. 

 This mineral, as is well known, is remarkable for its absence 

 from meteorites. Yet it doubtless does occur in minute grains 

 in a number of iron meteorites, since on dissolving them a 

 residue is left, the grains of which possess the properties of 

 quartz. Its occurrence in any stone or ironstone meteorite has 

 never yet been established. Pyrite. This mineral has been 

 reported a number of times, but sufficient proof to establish its 

 identity has not been given. Von Siemaschko reported from 

 the meteorite of Ochansk a brass-yellow pentagonal dodecahe- 

 dron of which, however, he gave no measurements. Daubree 

 found in the meteorite of Senhadja, bronze-yellow grains insolu- 

 ble in hydrochloric acid, soluble in aquaregia and altering easily 

 to iron sulphate. While these and other observations suggest 

 pyrite they are not conclusive. Salts soluble in zvater. Several 

 of the carbonaceous meteorites as well as one or two others give 



