33G Seyherl^s Analysis of the Maclureite 



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form liis works wiiliout a given time to do it. The prece- 

 diiitr aruLirncnts tend only (o show that the universe may be 

 finite or infinite, and that matter and finite spirits, or the V 

 ■work of creation may have been temporal or eternal. The 

 knowledge of what has occurred, and what exists in fact, if 

 it should be ever obtained, depends entirely on a different 



train of arguments. 



With much respect, 



your obedient servant, 



ISAAC ORR. 



Hartford, July 31, 1822. 



CHEMISTRY, PHYSICS, kz 



Art. XV. — Analysis of the Maculunite^ or Fliio-Silicafe of 

 Magnesia^ a new mineral ^pecits^ from Kew-Jersey ; hy 

 IIexry Sevbert. of Philadelphia. 



Head before the American Philosophical Society, on the I7th of May, lC2i'. 



Tfie colour of this mineral is generally wine jellovr, 

 sometimes reddish brown, and occasionally presents a green- 

 ish luie; reduced to powder, it is of a pale yellow colour. 

 Its lustre is most frequently vitreous, but some specimens 

 approach nearer to that of wax. In mass it is, for the most 

 part, opaque ; small fragments are generally transparent. 

 Its form is irregularly lenticular or spheroidal, bat it never 

 occurs regularly crystallized ; it exhibits a crystalline struc- 

 ture, and presents two cleavages in opposite directions. I 

 hj^ve not been able to obtain the primitive form by niechan- 

 ical division. The fracture in one direction, is distinctly 

 lamellar, in the opposite, it is less regular. Fragments in- 

 determinate. It scratclies fluorspar and glass, and gives 

 sparks abuiidantly with steel. It occurs imbedded in car- 

 bonate of lime, accompanied by carbonate of iron, and oc- 

 casionally by minute portions of mica. The size of the 

 spheroids varies from that of a pin's head, to several inches 

 in dirUfieter, and they often embrace carbonate of lime and 

 carbonate of iron as nuclei. Us speeific%ravity vanes 

 from 3.157 to 3.225. Before the blowpipe it is iiifusible 



