PHYSICAL AND LITERARY. 209 



A cauftic volatile alkali may alfo be obtain- 

 ed, by mixing fait ammoniac with half its 

 weight of a cauftic fixed alkali, or of magne- 

 fia which has been previoully deprived of its 

 air by fire ; and then fubmitting thefe mix- 

 tures to diftillation : Or merely by adding a- 

 ny ordinary volatile alkali to a proper quanti? 

 ty of a cauftic ley j for in this cafe the air 

 pafi!es from the volatile to the fixed alkali, by 

 a fuperior attraction for the laft, and, by a 

 gentle heat, the compound yields a fpirit fi- 

 milar to that prepared from fait ammoniac 

 and quick-lime. 



It is therefore probable, that, hqd yve al- 

 io a method of feparating the fi^ed alkali 

 from an acid, without, at the fame time, fa- 

 turating it with air, we ftiould then obtain it 

 in a cauftic form ; but I am not acquainted 

 with an inftance of this feparation in chemi- 

 ftry. There are two indeed which, at firft: 

 fight, appear to be of this kind j thefe are 

 the feparation of the fixed alkali from the ni- 

 trous acid by means of inflamed charcoal, 

 in the procefs for making 7iitrum Jixatum^ and 

 of the fame alkali, from vegetable acids p^ere- 

 ly by heat ; but, upon examining the pro- 

 dudt of each procefs, we find the alkali either 

 Vol. H. D d fulJy 



