on certain stony and metalline Substances, See. 181 
wise, were entirely covered with a black crust, the thickness 
of which was very inconsiderable. 
The stones which fell at Benares, are those of which the 
mineralogical characters are the most striking : I shall therefore 
begin the following description with them ; and shall afterwards 
make use of them, as objects of comparison, in describing the 
others. 
STONES FROM BENARES. 
These stones, as well as the others described in this Paper, 
whatever may be their size, are covered over the whole extent 
of their surface, with a thin crust, of a deep black colour : they 
have not the smallest gloss; and their surface is sprinkled over 
with small asperities, which cause it to feel, in some measure, 
like, shagreen, or fish skin. 
When these stones are broken, so as to shew their internal 
appearance, they are found to be of a grayish ash colour ; and 
of a granulated texture, very similar to that of a coarse grit- 
stone : they appear evidently to be composed of four different 
substances, which may be easily distinguished, by making use 
of a lens. 
One of these substances, which is in great abundance, appears 
in the form of small bodies, some of which are perfectly glo- 
bular, others rather elongated or elliptical. They are of various 
sizes, from that of a small pin's head to that of a pea, or nearly 
so: some of them, however, but very few, are of a larger 
size. The colour of these small globules is gray, sometimes 
inclining very much to brown : and they are completely 
opaque. They may, with great ease, be broken in all directions : 
their fracture is conchoid, and shews a fine, smooth, compact 
