Miscellaneous Notices, ^c. 159 



person of capital, and the requisite stock of information, 

 enter into the business of working the bed, I have no doubt 

 it would be profitable. 



Enclosed, is a small paper of a powder, found in Law- 

 rence County, about eighty miles west of Marietta, in a 

 bank of clay, and when first found, is in a liquid state, of 

 the consistence of cream, and nearly of that color; on dry- 

 ing it becomes blue. It is in separate parcels, confined to 

 small cells in the clay, in the manner that native quick -sil- 

 ver is sometimes found. It is said to be found in considera- 

 ble quantities. I should be glad of your opinion as to its 

 quality and use. 



The powder mentioned by Dr. Hildreth, is of a delicate 

 azure, much resembling powder blue, and was not unnatu- 

 rally, thought to be oxid of cobalt ; as however it loses its 

 color by the blow pipe, becomes magnetic, by being heated 

 on charcoal and very decidedly so, if grease be added be- 

 fore the heat is applied, it is probable that is similar to the 

 blue iron earth of mineralogists found in the diluvial coun- 

 try of New Jersey, and elsewhere. — Editor. 



August 8, 1828. 



Mexico. 



II. Extract of a letter to the Editor, from an American 

 resident in Mexico, dated Halcotal, near Temascaltepec, 

 July 13, 1828. 



1 . Geological character of the country. 



With respect to caverns in this country, I do not expect 

 to see many, if even any : I have yet met with very little 

 limestone. Lava, volcanic tufa, trachyte, clay slate and a 

 little granite, with porphyry, are the predominant rocks of 

 all the parts I have yet seen of Mexico. Volcanic tufa, tra- 

 chyte and lava, form about ninety nine parts in a hundred, 

 of the country yet visited. This country offers probably as 

 extensive a field for volcanic rocks and their debris, as any 

 that I have seen described ; none of which appear to be 

 recent : nor is there any volcano at present in activity ; a 

 fact which much surprised me, feeling almost certain, when 

 I came to the countrv, that I should see volcanos in ac- 

 tivity. 



