

118 POTASH. 



horizontal. Extensive formations of the slate coal a species of the 

 anthracite, is found on the island of R. I., which is very good for ma- 

 nufacturing purposes. According to estimates there are there 1000 

 million tons. At Worcester and other places in Mass, this coal also 

 abounds. 



POTASH, or Potassa, is also a vegetable product, and one of the 

 greatest importance in the arts of life, and as a staple product of our 

 country. Its name is from ashes and the pots in which the lixivium, 

 from which it is obtained, is boiled ; its old name was Kali, vegetable 

 alkali ; also salt of tartar, alkali of nitre, &c. The process of obtain- 

 ing it is to mix the ley of vegetable ashes with quick lime, and to boil it 

 down in iron pots ; the residuum is ignited, and the resulting substance 

 is potash. The purest is obtained from the action, in a red-hot pot, of 

 nitre 1 part, and 2 parts of tartar ; the basis of these salts is potash, 

 and the acids previously combined with them are given off. Plants 

 growing remote from salt water yield this alkali most abundantly, 

 herbs more than trees, branches more than the trunks of trees, and 

 leaves more than all. 



Potash is commonly obtained from the ashes of almost every spe- 

 cies of vegetable, by simply pouring water upon them. This dis- 

 solves the salt from its combinations, and the water is then evaporated ; 

 the residuum is carbonate of potash, and purified, the pearl-ash and the 

 salt of tartar of the shops. With nitric acid it forms salt-petre, or nitrate 

 of potash. As an article of commerce it is of a dark grey color, and 

 contains much vegetable extractive matter. After being procured as 

 above, it is heated in a reverbatory furnace, which dissipates the wa- 

 ter, destroys the extractive matter, and reduces it 15 per cent. The 

 potash is then white and pure, and hence called pearl-ash. It liquefies 

 on exposure ; and if adulterated with lime, as commonly, it falls into 

 powder. A highly important alkali soda is obtained from sea plants, 

 and used, with others, in the manufacture of glass and fine wares. No 

 class of salts, indeed, is more important in the arts than that afforded 

 by the combinations of potash. 



The Greeks and Romans were acquainted with caustic alkalies, and 

 soap was made, says Pliny, from tallow and wood ashes. In combina- 

 tion with acids, potash is found in both kingdoms ; in the inorganic 

 or mineral kingdom, combined with sulphur, nitric, silicic, and carbonic 

 acids, and in the organic, or animal kingdom, with phosphoric, sulphuric, 

 nitric, carbonic, and various organic acids ; thus being a component of 

 the three kingdoms. In rocks it is more abundant than soda, and in 

 vegetables more than in animals. To purify it, a solution in water is 

 evaporated in an iron vessel, and the hydrate is poured into moulds ; 

 or. pour it upon a bright iron plate, when drops rising on the surface 

 become hard on removal, and when hard, put it immediately into bot- 

 tles with ground stoppers. Pure hydrate of potash is white, extremely 



