PHYSICAL AND LITERARY. 175 



nefia does not emit air, or make an efFervef- 

 cence, when mixed with acids. 



The water, from its properties, feems to 

 contain a fmall portion of volatile alkali, 

 which was probably formed from the earth, 

 air, and water, or from fome of thefe com- 

 bined together \ and perhaps alfo from a 

 fmall quantity of inflammable matter which 

 adhered accidentally to the magnejia. When- 

 ever Chemifls meet with this fait, they are 

 inclined to afcribe its origin to fome animal, 

 or putrid vegetable, fubftance ; and this they 

 have always done, when they obtained it 

 from -the calcarious earths, all of which af- 

 ford a fmall quantity of it. There is, how- 

 ever, no doubt that it can fometimes be pro- 

 duced independently of any fuch mixture, 

 fmce many frefli vegetables and tartar afford a 

 confiderable quantity of it. ■ And how can 

 it, in the prefent inftance, be fuppofed, that 

 any animal or vegetable matter adhered to the 

 magnefia^ while it was diiTolved by an acid, 

 feparated from this by an alkali, and wash- 

 ed with fo much water ? 



Two drams oi magnejia were calcined in a 

 crucible, in the manner defcribed above, and 

 thus reduced to two fcruples and twelve 



grains. 



