216 Aerolites. 
cordingly, until their real nature was demonstrated by the 
aid of chemical analysis. One valuable specimen, found a 
few years ago, was shown to have derived its origin amongst 
the scoriw of an iron foundry ; another, picked up in the 
Isle of Wight, turned out to be a nodule of iron pyrites, 
similar in every respect to those which abound in the 
neighbouring chalk cliffs; and lastly, some aérolites of a 
peculiarly glassy appearance were found shortly after, of 
which it may, perhaps, suffice to say that the scene of this 
discovery was—Birmingham. 
When we come to examine the composition of meteoric 
stones, we find, in various specimens, a great diversity in 
their chemical structure. Iron is the metal most invariably 
present, usually accompanied bya considerable per-centage 
of nickel and cobalt; also five other metals, chromium, 
copper, molybdenum, manganese, and tin; but of all these 
iron is that which largely preponderates, forming sometimes 
as much as 96 parts inthe 100. Rare instances have, how- 
ever, been recorded where the proportion of iron has sunk 
so low as to form only 2 per cent., and the deficiency thus 
caused has been made up by a larger admixture of some 
earthy mineral, such as augite, hornblende, or olivine. 
Other ingredients, like carbon, sulphur, alumina, &c., are 
also found to enter, in different proportions, into the com- 
position of aérolites; the total number of chemical elements 
observed in them, up to this present date, being nineteen or 
twenty. It has been well remarked by an able writer, that 
no mew substance has hitherto come to us from without; 
and thus we find that all these nineteen or twenty elements 
are precisely similar to those which are distributed through- 
out the rocks and minerals of our earth; the essential 
difference between the two classes of compounds—celestial 
and terrestrial—being seen most clearly in the respective 
methods in which the component parts are admixed. 
In the outward appearance of aérolites there is one 
characteristic so constant that, out of the many hundred 
examples that have been recorded, one only (as far as we 
can ascertain) has been wanting in it. We refer to the 
black fused crust or rind with which the surface of meteoric 
stones is covered. It usually extends not more than a few 
tenths of an inch into the substance of the stone, and is 
supposed to result from the extreme rapidity with which 
they descend into the oxygen of our atmosphere, causing 
them to undergo a slight and partial combustion, which, 
however, from the short time necessarily occupied in their 
