1864. ] Mining, Mineralogy, and Metallurgy. 689 
Sciences de Vienne his continued researches on “ Metallic Irons which 
are probably non-Meteoric.” This examination is of the utmost 
importance, as tending to the settlement of a vexed question. We 
have no doubt but many of the masses of ‘‘ meteoric iron” so called, 
to which attention has been directed, will be found to be of terrestrial 
origin. We reserve, until the inquiry is yet further advanced, any 
extended notice of these investigations. It is sufficient to state, at 
present, that MM. Haidinger and Hornes consider that they have 
proofs that many of the specimens in the Imperial Museum of Vienna 
are not of meteoric origin. There can be no doubt but that many of 
the masses of iron reputed to be meteoric are so in reality; indeed, 
we appear to possess good evidence of the actual observation of their 
fall. It is, however, a question deserving serious inquiry, whether 
every mass of native iron containing manganese, cobalt, and nickel is 
of atmospheric origin. 
M. Cloéz and M. Pisani Lowe both instituted a very careful 
analysis of the aérolithe of Orgueil. In many respects this meteoric 
stone is found to resemble the mineral Serpentine, analysis giving the 
following constitution :—Silica 26°08, magnesia 17:00, protoxide of 
iron 21°60, lime 1°85, soda 2°26, potash 0°19, oxide of manganese 0°36, 
alumina 0°90, chromate of iron 0-49, oxide of nickel (with cobalt) 2°26, 
sulphuric acid 1:54, hyposulphuric acid 0°53, chlorine 0-08, sulphur 
5°75.* 
In connection with the inquiry on meteoric stones, M. Haidinger 
and others have investigated all the conditions under which graphite 
occurs in nature. 
A.report has been published,} from which we make a few extracts :— 
“One word on the formation, still so little known, of graphite (plum- 
bago, pencil lead). The presence of graphite in granite, gneiss, and 
diorite has renewed the disputes between the Neptunists and Plutonists. 
Graphite is well known to be nearly pure carbon, for it leaves in burning 
but a very small quantity of ash. Now, if these primitive crystalline 
rocks are of igneous formation, it is impossible to explain how graphite 
could co-exist with silicates of protoxide of iron without having reduced 
these salts. Judging merely by what takes place in blast furnaces, carbon 
reduces all oxides of iron at a high temperature. It must then be admitted 
that granite, gneiss, and diorite did not contain graphite when the mineral 
elements of these rocks, such as mica, hornblende, and other ferrous sili- 
cates, were in a state of fusion. Graphite then must have been subse- 
quently introduced into these rocks, but when, and how? Questions such 
as these are very difficult to answer satisfactorily. The most plausible 
hypothesis is that graphite has been introduced by the wet way into the 
crystalline rocks and substituted for one of the mineral components. Thus 
in the gneiss of Nassau (Bavaria) it takes the place of mica. 
“ Graphite is frequently to be met with in granulated limestone, a fact 
particularly interesting to geologists. Is limestone a product of eruption, 
or is it a sediment transformed by the action of heat? The presence of 
graphite is explicable by neither hypothesis. For at a certain tempera- 
ture, which need not be very high, carbon decomposes carbonate of lime. 
* «L'Institut, August 10, 1864. 
+ See ‘Cosmos,’ pp. 720, 725, 1864, and-* The Chemical News,’ August 6, 1864. 
