PHYSICAL AND LITERARY. 177 



the air ijS not retained in it: for the neutral 

 fait, into which it is converted, is the faine 

 in quantity, and in every other refped:, as if 

 the acid employed had not been previoully 

 faturated with mag7icfia^ but offered to the 

 alkali in its pure ftate, and had driven the 

 air out of it in their conflid:. It feems there- 

 fore evident, that the air was forced from 

 the alkali by the acid, and lodged itfelf in the 

 . magnefia. 



These confiderations led me to -try a few 

 experiments, whereby I might know what 

 quantity of air is expelled from an alkdi, or 

 ivom.}72agnefia, by acids. 



Two drams of a pure fixed alkaline fait, 

 and an ounce of water, were put into a Floren- 

 tine flafk, which, together with its contents, 

 weighed two ounces and two drams. Some 

 oil of vitriol diluted with water was dropt in, 

 until the fait was exadlly faturated ; which it 

 was found to be, when two drams, two fcru- 

 ples, and three grains of this acid had been 

 added. The vial with its contents now 

 weighed two ounces, four drams, and fif- 

 teen grains. One fcruple, therefore, and 

 eight grains were loft during the ebullition, 

 of which a trifling portion may be water, or 

 Vol. II. Z fomething 



