164? Chemistry. [Lecture 29. 



this mixture is exposed to a very strong heat, the 

 acid is either burnt or destroyed, and there arises 

 a vapour of a very disagreeable smell, in which 

 we can discover something of an inflammable 

 nature, but nothing like the acid. If we exa- 

 mine the remains of the compound, we find it a 

 little heavier, in consequence of the substances 

 with which it is united. 



The acetic acid is to be destroyed by heat 

 when mixed with alkali, and by itself when the 

 heat is properly applied. There are several sub- 

 stances which are converted into vapour before 

 we can give them a sufficient heat for inflamma- 

 tion : this is the case with spirit of wine, of which 

 the vapour only takes fire. Now if we manage 

 the acetic acid in the same manner, and heat it 

 till a copious vapour arises, the vapour will take 

 fire as other inflammable substances. No acid 

 is to be obtained from the inflamed vapour, and 

 nothing is left behind. 



Acetic acid is a compound of oxygen, hydro- 

 gen, and carbon. 100 parts contain 

 4-6-82 oxygen. 



6-35 hydrogen. 

 46-83 carbon. 



Tar tar ic acid. After the fermentation of 

 wine is over, there separates a quantity of a sub- 

 stance called tartar, which encrusts the casks. 

 In collecting it from the cask, it is necessary to 

 throw in a quantity of hot water, which dis- 

 solves the salt, and when the water is evaporated 

 the salts crystallize. Rhenish wine affords tar- 



