108 Prof. Silliman’s Description of the Maryland Aérolite. 
supplied the analysis—We add the following notice of the 
appearance of the stone. 
An excellent specimen, for which we are indebted to Dr. 
Samuel D. Carver, weighs four pounds five ounces. Its di- 
mensions are seven inches by three and four: its form is that 
of an irregular ovoidal protuberance, nearly flat where it was 
detached from the larger mass, and bounded by irregular 
curyes in the other parts of the surface. In all parts, except 
where it has been fractured, it is covered by the usual black 
vitreous coating, which in this case, especially when it is viewed 
by a magnifier, has more lustre than is common. This coat- 
ing is severed by innumerable cracks running in every direc- 
tion, and communicating with each other, so as to divide the 
surface into polygons resembling honeycomb or madrepore, 
and no undivided portion of the surface exceeds half an inch 
in diameter. 
This circumstance is much less apparent upon the aérolites 
of Weston (1807), L’Aigle (1803), and Stannern in Moravia 
(1808) : it appears to have arisen from the rapid cooling of the 
external vitreous crust after intense ignition. It is impossible 
to doubt that this crust is a result of great and sudden heat. 
In the Maryland aérolite it is not quite so thick as the back 
of a common penknife, and, as in that of Weston and Stan- 
nern, it is separated by a well defined line from the mass of 
the stone beneath. The mass of the stone is, on the fractured 
surface, of a light ash-gray colour, or perhaps more properly 
of a grayish white: it is very uniform in its appearance, and 
not marked by that strong contrast of dark and light gray 
spots, which is so conspicuous in the Weston meteorolite. 
The fractured surface of the Maryland stone is uneven and 
granular, harsh and dry to the touch, and it scratches window 
glass decidedly, but not with great energy. To the naked eye 
it presents very small glistening metallic points, and a few 
minute globular or ovoidal bodies scattered here and there, 
through the mass of the stone. With a magnifier all these 
appearances are of course much increased. ‘The adhesion of 
the small parts of the stone is so feeble, that it falls to pieces 
with a slight blow, and exhibits an appearance almost like 
grains of sand. The metallic parts are conspicuous, but they 
are much less numerous than the earthy portions, which, when 
separated, are nearly white, and have a pretty high vitreous 
lustre, considerably resembling porcelain. They appear as if. 
they had undergone an incipient vitrification, and as if they 
had been feebly agglutinated by a very intense heat. I can- 
not say that I observed in them, as M. Fleuriau de Bellevue 
did 
