gg^ ON THE ZEHR MOHEREH, 



they are dull, of a greenish grey color, fine earthy composition approaching to 

 impalpable, but nothing, in the most distant degree, resembling the lamellar 

 structure is to be detected. The fracture is perfect conchoidal. It is not, 

 however, obtained without difficulty, and the parts separate suddenly without 

 giving fragments. The character is quite peculiar to this substance. The 

 edo-es of the fracture, though sharp to the eye, feel quite smooth. The smell 

 is peculiar, and I may say indescribable. It is partly earthy, but this term alone 

 does not convey an adequate idea of it. Acids appear scarcely to have any ef- 

 fect, even when the powdered mineral is digested with them. Some iron, 

 ' however, is evidently taken up, as the solution, tested with Prussiate of Potassa, 

 assumes immediately a blue color. 



Before the Blow, Pipe it is infusible : when first exposed to its action, it 

 blackens, but the black color is dissipated by a continuance of the heat, and is 

 succeeded by a light buff, something similar to that of Wedgewood's ware. 

 In this operation it loses its peculiar smell. If the heat be continued, the 

 edges assume a white ashy appearance, but undergo no further change. 

 With Borax, on the wire, it fuses with considerable intumescence, and imparts 

 to the salt an illdefined, dirty, green color. With Soda, it fuses into a hard 

 brittle scoriaceous mass — with an increased dose, it forms an opaque bead, hav- 

 ing a dirty yellow or light brownish tinge. The bead gelatinises with acids. 



Leisure was wanting for a regular analysis, which, however, I propose 

 hereafter making. The above is quite sufficient to shew that it is perfectly 

 distinct from those examined by Dr. Davy, Like them, however, it would 

 appear to contain some Animal or Vegetable matter, at least if we are tojudge 

 by the transient black color, which it assumes under the Blow Pipe. It ap- 

 pears also to contain Protoxide of Iron, but by far the greatest proportion 

 of its substance must consist of Silica. It is unnecessary to say, that the 

 above characters equally separate it from every knov/n Mineral substance. 



