238 ALKALIES. 



It is given to animals, to relieve the inflation occasioned by eating 

 excessively of green grass, clover, lucerne, &c. It is of the most im- 

 portant and extensive use in practical chemistry. 



Remarks. 



Ammonia is one of those gases which destroy animal life, when 

 it is mingled, in only a small proportion, with the air that is respired. 



It was found by Chevallier in iron rust, in situations exposed to 

 animal effluvia ; it was formed when clean iron that had been ignited 

 was boiled in pure water, and it appears to be always formed when 

 iron decomposes water in contact with air ; the water affording the 

 hydrogen, and the air the nitrogen. 



It appears also to exist in natural iron ores, such as the red hema- 

 tite of Spain, the micaceous ore, and the Jenite of Elba.* 



It has already been mentioned that ammonia is formed when mois- 

 tened iron filings are placed in nitrogen over mercury, as ascertained 

 by Dr. Austin, in 1788. 



SEC. II. POTASSA. 



1. NAME. 



From the potashes of commerce ; and their name is obviously 

 derived from ashes, and the pots (called potash kettles,) in which the 

 lixivium is boiled down. Some of the old names were, vegetable 

 alkali salt of tartar salt of wormwood, and alkali of nitre, in allu- 

 sion to the principal sources from which the alkali is obtained. 



2. PROCESS OF THE ARTS.f 



The watery lixivium J of the ashes mixed with quick lime, being 

 boiled down in the iron pots or kettles, the residuum is ignited, and 

 then constitutes the potashes of commerce. Placed in a reverbera- 

 tory furnace, and stirred while the flame plays upon it, it becomes 

 white, and is then the pearlashes of commerce ; it is thus purified by 

 fire only, by the destruction of extractive and other combustible mat- 

 ter, and the dissipation of volatile principles, gases, &c. ; it loses gen- 

 erally about 10 or 15 percent, of its weight. || 



The purest alkali is obtained from the mutual action, in a red hot 

 iron pot, of nitre 1, and tartar 2 ; the basis of both salts being potash, 



* Am. Jour. Vol. XIII, p. 181. 



t To render this process intelligible, nothing more need be premised than that be- 

 sides impurities, the potash of commerce is found combined with carbonic acid, 

 which the lime detaches by its superior affinity, and thus liberates the alkali. 



\ This word is used to denote a lye made with ashes, and is derived from the 

 Latin word lix, denoting this preparation, and Lixa is a worker in this branch of the 

 Arts. Parkes. 



When wood is burned, the ashes constitute about l-200th part of its weight. 

 lire's Diet. 



|| See Dr. Roger's account in Am. Jour, Vol. VIII, p. 304. 



