33G ScyherCs Analysis of the Maclureile. 



form his works without a f;iven time to do it. The prece- 

 ding argum(;nts tend only to show that the universe may be 

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

 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, &c. 



Art. XV. — Analysis of the Macnhireite^ or Fluo-Silicate of 

 Magnesia, a new mineral species, from New-Jersey ; by 

 Henry Seybert, of Philadelphia. 



Read before the American Philosophical Society, on the I7th of May, 1822. 



The colour of this mineral is generally wine yellow, 

 sometimes reddish brown, and occasionally presents a green- 

 ish hue; reduced to pow .-, 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 tVagments are generally transparent. 

 Its form is irregularly lenticular or spheroidal, but it never 

 occurs regularly crystallized ; it exhibits a crystalline struc- 

 ture, and presents two cleavages in opposite directions. I 

 have not been able to obtain the primitive form by mechan- 

 ical division. The fracture in one direction, is distinctly 

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

 determinate. It scratches fluor spar and glass, and gives 

 sparks abundantly 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 diameter, and they often embrace carbonate of lime and 

 carbonate of iron as nuclei. Its specific gravity varies 

 from 3. lo7 to 3.225. Before the blowpipe it is infiisible 



