PHYSICAL AND LITERARY. 213 



ing the precipitation, and was confequently 

 converted into a neutral fait by attrading the 

 acid. The properties therefore of the mix- 

 ture can only be referred to a lime, as is in- 

 deed fufficiently evident from the crufl which 

 is peculiar to lime-water. 



I was therefore allured by this experiment, 

 that an alkali does really lofe a part of its air, 

 and acquire a degree of caufticity, by the pro- 

 per application of heat 5 but finding by 

 feveral trials, that the degree of caufticity 

 which; it had thus acquired was but weak, 

 and that the quick-lime produced in this ex- 

 periment was exhaufted and rendered mild 

 by a fmall quantity of water, I expofed the 

 crucible together with that half of the al- 

 kali which remained in it to a ftronger fire, 

 in order to expel a larger quantity of air, and 

 render it more remarkably cauftic ; but the 

 whole of it was diflipated by the force of the 

 heat, and the black lead, which ftill retained 

 the form of a loofe and fubtile powder, 

 yielded little or nothing to water. 



We learn then from the above experiment 

 the reafon why the alkali newly obtained 

 from the afhes of vegetables is generally of 

 ^he more acrid kinds of that fait. It never 



appears 



