416 REPORT—1868. 
Langeac. The fusion of iron alloyed with nickel and phosphuret of iron 
produced reticulated figures on the etched sections, which, although not so 
regular as those of Widmanstiatten, were yet perfectly distinct. The forma- 
tion of small spherules of bisilicate was also repeatedly noticed in the re- 
sults of terrestrial fusions, which are abundant in certain aérolites; while 
the graphitic-looking friction-planes met with in many meteorites could be 
perfectly imitated, by rubbing together fragments of the reduced iron-bear- 
ing residue of the fusion of terrestrial rocks. 
The serpentine or hydrated class of magnesian rocks were next submitted 
to experiment—first, in crucibles lined with calcined magnesia, and afterwards 
alone. The result in the first case is a perfectly crystalline peridot, and in 
the second case a group of mixed crystals of peridot and enstatite. When 
the crucibles are lined with charcoal, the resulting mass contains a highly 
nickeliferous metallic iron*. Most of the serpentines also contain chromite, 
which was first pointed out by Laugier as an ingredient of the most constant 
and regular occurrence in meteorites. 
Serpentine, basaltic peridot, and lherzolite may accordingly be regarded 
as the chief terrestrial rocks of a meteoric type. With granite and gneiss, 
the two staple foundations of the earth’s crust, meteorites have no features 
in common,—neither orthose, felspar, mica, quartz (the meteoric iron of To- 
luca, according to G. Rose, alone excepted), tourmaline, nor any of the com- 
mon granitic silicates being found in them. But they agree closely with 
those basic rocks whose origin is deeper-seated than the granite, and which 
only reach the surface in volcanic eruptions. They consist most largely of 
peridot, which is, perhaps, only entirely absent from the three aluminiferous 
meteorites already mentioned. Its great specific gravity and general distri- 
bution in volcanic rocks, its avidity for silica (directly opposed to granite as 
the most basic of all the known silicates), and. lastly, its abundant occur- 
rence in aérolites appear to constitute the character of peridot as the true 
“ universal scoria.” 
Inasmuch as carbon, in the form of graphite, is rarely found in meteoric 
iron, it could not be the reducing agent to which aérolites appear to owe 
their low degree of oxidation; while their reduction by hydrogen would give 
rise to the formation of water and of hydrates, which are only known to 
exist, as M. Wohler has shown, in the carbonaceous meteorites of Orgueil, 
Kaba, and Cold Bokkeveldt. To explain the presence of such ingredients as 
metallic iron and unoxidized sulphur and phosphorus in meteorites, a process 
of oxidation of the original substances may, on the contrary, be supposed to 
have taken place, which was either incomplete on account of a deficiency of 
oxygen, or otherwise imperfect by reason of some interruption arising in its 
action. In order to submit the effects of such a process to experiment, un- 
oxidized siliciuret of iron was heated in a crucible, in contact with calcined 
magnesia, with a very slight access of air. Silica was thus produced, and it 
combined with the calcined magnesia in the form of peridot, while the iren 
was left in a metallic state. In another experiment, an alloy of iron con- 
taining 9 per cent. of nickel, with sulphuret and phosphuret of iron, silica, 
and magnesia, were heated together in a Schloesing’s gas-furnace, with the 
same precaution as before of admitting a slight access of air. The resulting 
peridot was olive-coloured, containing iron, and was without a trace of nickel, 
exactly as it is found enclosed in the meteoric irons of Pallas and Atacama, 
* The chemical analyses in this and the following experiments were conducted by M. 
Stanislas Meunier, the assistant in the geological laboratory of the Paris Museum of 
Natural History. 
