144 Chemistry. [Lecture 29. 



lye already described, and then burning them; 

 the ashes so produced are called pot-ashes, and 

 are prepared in Russia, and on the coasts of the 

 Baltic. Many uses to which potass is applied 

 do not require it to be very pure. It is also 

 easily obtained from a saline substance which is 

 deposited from wine called tartar, and when 

 prepared from this it is called salt of tartar, 

 which, when exposed to the air, is deliquescent, 

 and for that reason was formerly called oil of 

 tartar. It has much the same qualities and uses 

 as soda. 



Long since, while the two fixed alkalies were 

 only suspected to be compound bodies, the vola- 

 tile, or AMMONIA, was proved to be such. It is 

 indeed a combination of nitrogen or azote with 

 hydrogen, and a hundred parts of ammonia con- 

 tain about eighty parts of nitrogen and twenty 

 of hydrogen. This has been shown by the 

 experiments of Berthollet, of Dr. Austin, and 

 many modern chemists, who have not only sepa- 

 rated ammonia into its component parts, but 

 have recomposed it from a union of the two 

 ingredients. 



Ammonia has been long known in commerce 

 under the names of volatile alkali, volatile salt, 

 and spirit of hartshorn. Its volatility is such, 

 that under the ordinary pressure of the air it is 

 constantly flying off in vapour, which, though 

 we cannot see, we are sensible of by the smell. 

 Its acrimony does not produce its effects so con- 



