82 SECRETIONS- 



esculent fruit of many plants, communicating a swee •: 

 and usually an agreeable taste. 



ACIDS exist in many plants, and when sufficiently 

 abundant, they communicate their own peculiar taste 

 to the organs which contain them. Thus for example 

 the leaves of the Sorrel, and the fruit of the Lemon 

 tree, are both sour. Chemistry has ascertained the 

 existence of several peculiar acids, which exist in the 

 'eaves and other parts of different plants ; they have 

 usually a sour, sometimes an astringent taste, but they 

 are better known by their effects on the vegetable col- 

 ours. The Prussic acid, which may be obtained by 

 distilling the leaves and kernel of the Peach tree, pos- 

 sesses the flavour of bitter almonds, and is, when used 

 to excess, a poison of the most virulent kind. This 

 should teach us caution in the use of the distilled wate r 

 of the Peach, which possesses to a greater or less ex- 

 tent, the dangerous properties of the acid in question. 

 The Tartaric acid exists in the juice of the grape, and 

 constitutes the principal ingredient of the well known 

 salt, Cream of tartar. It is deposited on the bottom of 

 wine casks, where it is found in sufficient abundance to 

 supply the apothecary with a very important medicine. 

 The Malic acid exists in the juice of Apples, Bar- 

 berries, Plumbs, Currants and Strawberries, and it is 

 essentially different from those which communicate a 

 sour taste to the Sorrel and Lemon. Jellies contain 

 the peculiar acids of the fruit from which they are 

 procured, united with sugar, and in some cases with 

 mucilage or starch, and the agreeable healthy qualities 

 of most fruits depend on the vegetable acid which they 

 contain. 



TANNIN.— If nutgalls or grape seeds are pulverized 

 and dissolved in cold water, the solution when evapo- 



