SECT. XXVI. ALKALIES. 



When pure it is white and semi-transparent, and 

 is extremely caustic and deliquescent. It dissolves 

 all soft animal substances, and changes vegetable 

 blues into green. It dissolves alumina, and also a 

 small quantity of silex, with which it fuses into 

 glass by the aid of fire. It had been long suspected 

 by chemists to be a compound substance ; and ac- 

 cording to the notable discovery of Sir H. Davy, its 

 component parts are at last ascertained to be a 

 highly inflammable metal, which he denominates 

 potassium, and oxygene one proportion of each.* 



Soda is found chiefly in marine plants, from the 

 ashes of which it is obtained by means of lixivia- 

 tion. It exists in great abundance in Salsoa Soda, 

 Zoster a maritima, and in various species of Fuci. 

 It is generally obtained in the state of a carbonate, 

 but is purified in the same manner as potass, to 

 which it is similar in its properties ; but from which 

 it is easily distinguished by its forming a hard soap 

 with oil, while potass forms a soft soap. It consists, 

 according to Sir H. Davy, of one proportion of a 

 metal which he denominates sodium, and two pro- 

 portions of oxygene. -f- 



Such are the only vegetable alkalies, and the Soda. 

 modes of obtaining them. They a r e found generally 

 in the state of carbonates, sulphates, or muriates, 

 salts that form beyond all comparison the most 

 abundant ingredient in the ashes of green herbace- 

 ous plants whose parts are in a state of vegetation. 

 * Elem of Agri. Chcm. p. 98. f Ibid. 



2 H 2 



