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the other acids by its aromatic odour, and by its ex- 

 treme volatility. 



Malic acid may be obtained from the juice of 

 apples, barberries, plums, elderberries, currants, 

 stawberries, and raspberries. It forms a soluble salt 

 with lime ; and is easily distinguished by this test 

 from the acids already named. 



Acetic acid, or vinegar, may be obtained from 

 the sap of different trees. It is distinguished from 

 malic acid by its peculiar odour ; and from the other 

 vegetable acids by forming soluble salts with the alka- 

 lies and earths. 



Gallic acid may be obtained by gently and gradu- 

 ally heating powdered gall nuts, and receiving the vo- 

 latile matter in a cool vessel. A number of white 

 crystals will appear, which are distinguished by their 

 property of rendering solutions of iron, deep purple. 



The vegetable prussic acid is procured by distil- 

 ling laurel leaves, or the kernels of the peach, and 

 cherry, or bitter almonds. It is characterized by its 

 property of forming a blueish green precipitate, when 

 a little alkali is added to it, and it is poured into solu- 

 tions containing iron. It is very analogous in its pro- 

 perties to the prussic acid obtained from animal sub- 

 stances ; or by passing ammonia over heated charcoal ; 

 but this last body forms, with the red oxide of iron, 

 the deep bright blue substance, called Prussian blue. 



Two other vegetable acids have been found in 

 the products of plants ; the morolyxic acid in a saline 

 exudation from the white mulberry tree, and the kinic 

 acid in a salt afforded by Peruvian bark ; but these 



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