272 ESSAY XXV. 



sugar, and on the difference between them. Now, when 

 must has undergone the fermentative process, its acid 

 appears under the two forms of vinegar and of tartar. Are 

 both these acids newly generated by the process ? or but 

 one ? or are they only separated ? To the production of 

 tartar, fermentation is not necessary ; for, according to 

 Rouelle (Bucquet Introd. a I'dlude des corps natur., t. ii. 

 p. 177), it may be procured from the juice of unripe 

 grapes. Pure acid of tartar consists, after distillation per 

 se, of an empyreumatic acid, and the coal that is left behind 

 of oily particles and calcareous earth (Bergmann, de tiibo 

 ferrum, Sec. xu.), may not then the acetous acid be mere 

 acid of tartar, which did not meet with alkaline salt and 

 earth enough with which it might combine and become 

 more fixed ; but, on the contrary, attracted more subtile 

 oily particles, and thus became more volatile ? That fixed 

 vitriolic acid is converted by phlogiston into the sulphureous 

 acid which is so volatile that the acetous acid may acquire 

 its characteristic properties, from the want of fixed con- 

 stituent parts with which it might unite, may be deduced 

 from the changes which it undergoes when combined with 

 some fixed matter, and then distilled. Acetated vegetable 

 alkali (terra foliata tartari) yields, according to Mr. Beaume 

 (Chym. exp. et raison, t. ii. p. 21), on distillation by 

 itself, but 4-5-5- of pure acid. All the rest of the acid 

 employed for saturation is totally destroyed, and the 

 residuum, both in the retort and receiver, quite alkaline, 

 just as the acid of tartar is almost wholly destroyed by 

 dry distillation, the empyreumatic acid which is obtained 

 being very weak. According to Beaume (t. i. p. 315), if 

 calcareous earth, egg-shells for example, be dissolved in 

 vinegar, and the crystallised salt be distilled, ff of a red 

 and very spirituous and inflammable fluid, that smells like 



