COMPOSITION or PLANTS. 237 



table juices, after they had been reddened by acids. Besides, 

 it shoots out into fine needle-formed, or prismatic crystals, and 

 is scarcely soluble in hot water, but very much so in alcohol. 

 Of precisely the same nature is Strychnin, which Pelletier has 

 found, by means of corrosive alkali, in the crow's eye, and in 

 Ignatius' beans. Many strong-tasted matters owe their ori- 

 gin, probably, to the same element ; (Annales de Chimie, 

 tom. X., 1819.) 



Other peculiar substances have quite different relations, al- 

 though they stand in the same class with that we have now 

 considered, as being the bases of acids. Cinchonin, which is 

 found in the chinarinde, combined with the acid of cinchona, 

 ]X)lychroit in saffron, and inulin in the Alant, are but indivi- 

 dual examples of such matters, being formed by different 

 proportions of the same elements of plants* 



363. 



From all these facts we conclude, that the simple elemen- 

 tary bodies which plants take up from the soil, are united 

 and separated again in the most varied and multiplied pro- 

 portions, and that it is in this manner that all the more inti- 

 mate constituents of plants are produced. If, with the view 

 of illustrating this conclusion, we attend to the relations of the 

 vegetable acids, we perceive that the further vegetation has 

 proceeded, there is less oxygen, and more hydrogen and azote 

 in the acids. We remarked formerly (351.), that the oxalic 

 acid, next to carbonic acid, is the richest in oxygen. To 

 these succeeds the tartaric acid, which we find in a free state 

 in the pith of the Tamarind, and in other plants, combined 

 with a base. It is distinguished from the oxalic acid only by 

 4 per cent, additional of hydrogen, and 1 per cent, less of 

 oxygen. The citric acid, which is found in great quantity 

 in orchard fruits and berries, contains as much hydrogen, 9 

 per cent, more of carbon, and 10 per cent, less of oxygen, 

 than the tartaric acid. The malic acid is still richer in car- 

 bon, but less plentifully stored with oxygen, on which account 

 it is possible, by means of nitric acid, to change it into oxalic 

 acid. 



