viii Letter from Professor Hall. 



perature. From a combination of carbon and potash, 

 or soda, results a black mass, which suddenly inflames 

 when placed in contact with the air, or plunged in 

 water. The metal is obtained perfectly pure, when 

 iron is employed instead of carbon. 



Messrs. Thinard and Guy-Lussac have already sub- 

 mitted the metal to a number of interesting trials, the 

 success of which will soon be made public. Much is 

 expected from their labours; and, indeed, it is gene- 

 rally believed, here, that this discovery will gradually 

 lead to others of equal, and, perhaps, superior import- 

 ance. As the metals of potash and soda can now be 

 casilv procured, in abundance, the relations, which 

 they sustain to other substances, will undoubtedly be. 

 made the subject of chemical investigation. 



It is Mr. Davy's opinion, " that alt the different 

 earths consist of bases of a peculiar metallic nature, 

 having a very strong affinity for oxygen, by uniting 

 with which, they form those earths respectively." He 

 believes that he has already made visible, by the assist- 

 ance of galvanism, the basis of the one called barytes. 



I make this communication, Sir, in hope that the 

 subject may be sufficiently interesting to engage you, 

 and other philosophers on your side the Atlantic, to 

 unite your labours with those of the English and 

 French in this new field of physical inquiry. 



I am, &c, 



Frederick Hall. 

 Pari*, March 24th, 1808. 



