VEGETABLE ACIDS. Ilj7 



it should be clarified in order to free it from the mucilage, 

 which would cause it to ferment ; and care must be taken 

 so to place the casks, that the liquor will not be liable, by 

 being jolted, or shaken, to have the mucilage, which has 

 been precipitated, mixed again with it. 



When wine has been well fermented, and all its muci- 

 lage decomposed or precipitated, it is no longer capable of 

 turning sour. I Jiave kept some of the red wine of the 

 south in uncorked bottles, upon a terrace exposed to the 

 heat of the sun during a whole summer, without its under- 

 going any other change than that of completely losing its 

 color ; the coloring principle being precipitated in the form 

 of pellicles or membranes, which remained swimming in the 

 liquor. Towards the end of August, I put into two of these 

 bottles, containing equal quantities, the juice of two apples, 

 and at the end of a month the liquor was converted into 

 vinegar. 



The care which is necessary to preserve wine unchang- ' 

 ed, indicates the course to be pursued for converting it into 

 vinegar : all that is required to accomplish this, is to expose 

 the liquor to the air at a temperature of between 70° and 80° 

 Fahrenheit : when the liquor does not contain any fermenta- 

 tive matter, a portion of yeast may be added to it; or it may 

 be put into casks, which are impregnated with acetic acid or 

 which contain sour lees. 



I shall not undertake to enumerate the various uses to 

 which vinegar is applied upon our tables, or in our kitch- 

 ens ; its employment in the arts is at least as extensive 

 and as varied; aromatic plants are distilled with it for 

 perfumes, and it is used for dissolving iron, copper, lead, 

 and alumine, to form mordants in dyeing, and colors in 

 stamping. 



Messrs. Gay-Lussac and Thenard found acetic acid to 

 contain carbon, oxygen, and hydrogen in the following 

 proportions ; 



Carbon . 50.2-24 



Hydrogen 5.629 



Oxygen 44.147 



Prus sic Acid. Bitter almonds, peach- stones, and the 

 leaves of the laurel, when distilled, afford an acid, which 

 forms, with a solution of iron and a small quantity of alka- 

 li, a greenish blue precipitate : this acid bears a strong 

 resemblance to that which is extracted from some animal 

 substances, and which, when combined with iron, forms 

 Prussian blue. 



