PHYSICAL AND LITERARY. 193 



as much of the fuperfluous quick-Hme might 

 pofTibly be dilTolved by the ley as would be 

 diffolved by pure water, or the ley would 

 contain as much lime as lime-water does. 



V. We have fliewn in the former experi- 

 ments, that abforbent earths lofe their air 

 when they are joined to an acid ; but recover 

 it, if feparated again from that acid, by means 

 of an ordinary alkali : the air paffing from 

 the alkali to the earth, at the fame time that 

 the acid pafTes from the earth to the alkali. 



If the cauftic alkali therefore be deftitute 

 of air, it will feparate magnefia from an acid 

 under the form of a magnefia free of air, 

 or which will not effervefce with acids j and 

 the fame cauftic alkali will alfo feparate a cal- 

 carious earth from acids under the form of 

 a calcarious earth deftitute of air, but fatu- 

 rated with water, or under the form of flaked 

 lime. 



These were all neceflary conclufions from 

 the above fuppofitions. Many of them 

 appeared too improbable to deferve any fur- 

 ther attention : fome however, I found upon 

 refle£tion, were already feconded by expe- 

 rience. Thus Hoffman has obferved, that 

 quicklime does not effervefce with fpirit of 

 Vol. II. B b vitriol, 



