196 ESSAYS AND OBSERVATIONS 



dried, weighed one dram and fifty eight 

 grains. It was fimilar in every trial to a fine 

 powder of ordinary chalk, and was therefore 

 faturated with air which muft have been fur- 

 nirhed by the alkali. 



A dram of pure fait of tartar was diflblved 

 in fourteen pounds of lime-water, and the 

 powder thereby precipitated, being carefully 

 colledted and dried, weighed one and fifty 

 grains. When expofed to a violent fire, it 

 was converted into a true quick-lime, and 

 had every other quality of a calcarious earth. 



This experiment was repeated with the 

 volatile alkali, and alfo with the foflll or al- 

 kali of fea-falt, and exadly with the fame 

 event. 



The third prcpofition had lefs appearance 

 of probability than the foregoing ; but, as 

 an accurate experiment was the only teft of 

 its truth, I reduced eight grains of perfedl 

 quick-lime made of chalk, to an exceedingly 

 fubtile powder, by flaking it in two drams of 

 diftilled water boiling hot, and immediately 

 threw the mixture into eighteen ounces of 

 diftilled water in a flalk. After fliaking it, 

 a light fediment, which floated thro' the li- 

 quor, was allowed to fubfide ; and this, when 



collected 



