ON VEGETABLE ACIDS 273 



ernpyreumatic acetous ether, and reddens tincture of turnsol, 

 is got. This also shows the change that has been wrought, 

 and the reduction of the strength of the former acid. The 

 acid in sugar of lead is in like manner entirely destroyed 

 by distillation (Macquer's Diet., vol. i. p. 328 of the German 

 translation). It is still further in confirmation of this that 

 must, distilled even before fermentation, yields nothing but 

 an empyreumatic acid, a kind of spirit of tartar. Whoever 

 shall doubt of the great difference which the close com- 

 bination or absence of earthy particles occasions in an acid, 

 would do well to compare lime combined with somewhat of 

 an excessive portion of vitriolic acid, with the same acid 

 uncombined (Beaume, loc. cit.,p. 273). Let him at the same 

 time imagine the earth to be so intimately combined as to 

 be inseparable. In this manner may, I think, tartar be 

 conceived, since, according to Bergmann's experiment, it 

 contains calcareous earth ; but it is united with acid in 

 excess, tastes sour, and is soluble. The contrary appears 

 when acid of tartar is completely saturated with lime; for 

 the selenite is exceedingly difficult of solution, and has 

 scarce any taste. 



Is it then a conjecture altogether improbable that vinegar 

 and tartar have for their basis the same species of acid, and 

 that this acid is only combined with a greater quantity of 

 subtile oil in one case, and with more earth in the other ? 

 Will it not be possible to bring vinegar again in some 

 measure nearer towards the state of tartar ? In order to 

 accomplish this, we must endeavour to take away the fine 

 volatilising phlogiston of the former, to combine it with 

 more fixed matter, and to restore its grosser oil. The latter 

 seems to be extremely difficult, nor will the former be easily 

 effected. Mr. Westrumb (Chem. Ann., St. iii. S. 340), in 

 examining whether vinegar did not contain acid of sugar, 

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