160 Scientific Notices-^Mineralogp. [Feb. 



from the larger mass, and bounded by irregular curves in the 

 other parts of tlie 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 coating is severed by 

 innumerable cracks running in every direction, and communi- 

 cating with each other so as to divide the surface into polygons 

 resembling honey-comb or madrepore, and no undivided portion 

 of the surface exceeds half an inch in diameter. 



This circumstance is much less apparent upon the aerolites of 

 Weston (1807), L'Aigle (1803), and Stannern, in Moravia (1808): 

 it appears to have arisen from the rapid coolmg 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 aerolite it is not quite so ihick as the back of a 

 common penknife, and, as in that of Weston and Stannern, 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, 

 bvit they are much less numerous than the earthy portions, which, 

 when separated, are nearly white, and have a pretty high vitre- 

 ous 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 cannot say 

 that I observed in them, as M. Fleuriau de Bellevue did in the 

 aerolite of Jonzac (Jour, de Phys. torn. xcii. p. 136), appearances 

 of crystallization, although it is possible there may have been 

 an incipient process of that kind, especially as the small parts 

 are translucent.* The Maryland stone is highly magnetic ; 

 pieces as large as peas are readily hfted by the magnet, and 

 that instrument takes up a large portion of the smaller fragments. 



♦ This vitreous appearance, I believe, has not been observed before (at least as far as 

 appears in any account that I have seen). It seems to have resulted from intense heat ; 

 the same doubtless which covered the exterior with the black crust, and the difference of 

 the two is probably to be ascribed to the one being covered and coHipressed, and to tile 

 otiier being on the out«ide. 



