130 



tions of minute particles of nickel-iron, perhaps due to the 

 reducing action of hydrogen at a high temperature. Others, 

 as Chateau-Renard (230 X), Pultusk (313 V), and Ales- 

 sandria (280 P), present what in terrestrial rocks would 

 probably be called faults: in some cases the fissures are 

 seen to have been filled with a fused material after the 

 spherules have been broken and one side of the fissure has 

 glided along the other. These peculiarities of structure 

 would indicate that the small body which reaches the earth 

 is only a minute fragment of a much larger mass. 



As to the conditions under which compounds such as 

 have been mentioned as occurring in meteorites, can have 

 been formed, we may assert that they must have been very 

 different from those which at present obtain near the earth's 

 surface : in fact, it is difficult to imagine that the unstable 

 sulphides can either have been formed or have remained un- 

 decomposed under circumstances in which water and atmo- 

 spheric air have played any prominent part. Still, what 

 little we do know of the inner part of our globe does not 

 shut out the possibility of the existence of similar compound 

 and elementary bodies at great depths below the surface. 

 Daubree, after experiment, inclines to the belief that the 

 iron is due, in many cases at least, to reduction from an 

 olivine rich in diferrous silicates, and this view acquires some 

 additional probability from the presence of the gases hydro- 

 gen and carbonic oxide in several meteoric irons: the existence 

 however, of such siderolites as that of Krasnoyarsk (122 K), 

 which is still rich in ferruginous olivine and yet presents no 

 traces of the intermediate magnesium silicate (enstatite), offers 

 a weighty objection to the general application of this view. 



We must now briefly refer to the theories which have been 

 framed to explain the origin of these bodies. The old theories 

 that they are ordinary stones struck by lightning, or carried 

 to the sky by a whirlwind, or are concretions in the atmo- 

 sphere, or are due to the condensation of a cloud coming 

 from some volcano, or have been shot recently from terrestrial 

 volcanoes, are all seen to be quite inconsistent with later ob- 

 servation. The suggestion of Laplace that they come from 

 modern volcanoes of the moon, although mathematically 



