330 EXPERIMENTS RELATIVE TO METEORITES. 



reduced to pliosphnrets, so that the final product of the action of the hydrogen 

 presents a great chemical analogy with the meteorites. 



IMITATION OF METEORITES OF THE COMMON TYPE BY OXIDATION OF 



SILICIURBTS. 



There is a second method by whic^i we are enabled to effect the imitation of 

 meteorites. It is the inverse of the preceding, and consists in heating the domi- 

 nant bodies of meteorites of the common type, other than the oxygen, that is to 

 say, the iron, the silicium, and the magnesium, in an atmosphere inct)mplotely 

 oxidizing, and by conducting the process not only to roasting, but fusion, or in 

 effect to scorification. 



By exposing to the high temperature of the gas blow-pipe siliciuret of iron 

 contained in a brasque of magnesium we obtain a perfect imitation, in all that is 

 essential, of meteorites of the common type. The iron is separated, as well in 

 a metallic state as in that of a silicate, and peridot is produced, partly in a crys- 

 tallized form. This peridot presents divers shades, among others the olive tint 

 which is habitual to it in natm-e. * ******, 



§ 2. DEDUCTIONS AS RESPECTS THE ORIGIN OF THE PLANETARY BODIES 

 FROM WHICH METEORITES ARE DERIVED. — TEMPERATURE. 



In the first place, is it possible to form an idea of the temperature at which 

 the cosmical bodies in question are formed ? 



The experiments above stated seem to authorize us to assign to it certain limits. 

 The temperature was doubtless high, since the anhydrous silicates, such as peri- 

 dot and pyroxene, were produced. It appears, however, to have been lower than 

 that at wliich the preceding experiments were conducted. Two facts lead us to 

 this supposition. Tlie high temperature employed in the laboratory residted in 

 the formation of silicates in well defined and voluminous crystals; such as are 

 never met with in meteorites. It is worthy of remark, in fact, that the silieated 

 substances, which compose the meteorites of the common ty})e, are always in the 

 state of very small and confused crystals, notwithstanding the strong tendency 

 w'hich they have to crystallize. Were we to seek some analogy in nature, we 

 should say that the crystals obtained by the fusion of meteorites recall the long 

 needles of ice which liquid water forms in congealing, while the fine-grained 

 structure of natural meteorites resembles rather that of hoar-frost or snow, formed, 

 as we know, by the immediate transition of atmospheric vapor to a solid state, 

 or perhaps that of the Hour of sulphiu' produced under analogous conditions* 

 Moreover, in meteorites the form of the grains of iron is wholly irregular and, 

 as it were, tubercular, (Sierra de Chaco). But the temperature employed in 

 these exj)eriments caused the metallic granules to take, in general, a spherical 

 form ; which is never observed in meteorites. 



I have sought to imitate the mode of dissemination of metallic iron in silicate;?, 

 as it occurs in common meteorites, by exposing to a high temperature an inti- 

 mate mixture of reduced iron and Iherzolite. After fusion of the whole, the 

 particles of iron reunite in numerous and still very small grains, the globular 

 form of which, easily distinguishable, especially after the specimen has been 

 polished, contrasts with the grains of tubercular form disseminated in the mete- 

 orites. 



Let it be distinctly observed that, in all cases, this original heat does not 

 exist when the masses penetrate into our atmosphere. In effect, the carbon- 

 aceous meteorite of Orgueil is composed of a stony matter, holding in combina- 

 tion, or in intimate mixture, even in its central parts, water and volatile sub- 

 stances ; it is, by reason of so sensitive a nature, a true thermomete? a maximum, 

 which indicates to us that these bodies could not be else than cold at the moment 



