82 On the DeweyVtte. 



About two years ago, and before having seen the description of 

 Dr. Emmons, I made a mineralogical and chemical examination 

 of the mineral under consideration ; the acconnt of which has lain 

 by me unpublished until this moment, and which I here give entire, 

 as it was then drawn up. 



In the spring of 1825 I visited the locality of this substance in 

 company with Dr. Emmons. It was embraced in Serpentine, and 

 occurred in veins from one quarter, to one and a half inches in thick- 

 ness. These veins were disposed, for the most part, horizontally ; and 

 were situated directly in the bed of a small stream, which at the time 

 we visited the spot, was sufficiently low to admit of our obtaining a 

 tolerable supply of specimens ; although considerable masses of ser- 

 pentine were often to be removed by the hammer and chisel, in fol- 

 lowhig the veins. 



Description. 



Massive. Fracture even : imperfectly conchoidaL 

 Lustre vitreous inclining to resinous : in degree, varying from shin- 

 ing to dull : color white, tinged in veins with yellow, green and red : 

 translucent. Streak white. The most translucent fragments, after 

 immersion in water, afford by transmitted light, a bluish color. 



Brittle. Easily frangible, especially if thrown into water, when a 

 large mass may be broken into fragments by the mere strength of 

 the hands. Hardness intermediate between that of Calcareous spar 

 and Fluor, and may be expressed by the scale of Mohs, as =3,3. Sp. 

 gr. =2.246. 



Before the blowpipe it decrepitates violently : but when heated 

 slowly, it loses its lustre, becomes opaque, and fuses with great dlfTi- 

 c'ulty upon die edges, Into a white enamel. In the state of powder, 

 with borax, it forms a colorless transparent glass. 



Analysis. 



50 grains, in the state of an impalpable powder, heated for ono 

 hour in a platina crucihle, lost 10 grains in weight, and presented no 

 perceptible change in color. Mingled with three times its weight of 

 potash, it was exposed to a dull red heat in a silver crucible during 

 thirty minutes. The resulting mass presented the appearance of hav- 

 ing undergone a perfect fusion, and when cold was free from metallic 

 stains. It was separated from the crucible by the affusion of warm 

 water, and treated with an excess of muriatic acid. The colorless 



