26 MINUTES OF 





On the component Principles of Fegetables. 



acid whicli is called — the pyroligneous. It appears to be the last product of the 

 elaboration of vegetable organs. Treated with the nitric acid, it is capable of 

 passing into three or four different states of acidity. It is, however, insoluble in 

 water and most other menstrua. It should seem, that this ligneous matter con- 

 sists of mucilage united with an extraordinary proportion of oxygen. 



XV, Concerning Extract. 



The juices of plants, obtained from them, by mechanical pressure, by the 

 simple infusion of the plant in a liquid, or by its decoction in boiling water; in- 

 spissated ; and at last evaporated to dryness; afford a dry, brown matter, slightly 

 deliquescent in the air, and soluble in water, which is the extract. This matter 

 yields by distillation, an, acid, a small portion of ammoniac, and some oil. It ab- 

 sorbs oxygen from the atmospherCj and becomes gradually insoluble, in conse- 

 quence of this absorption. It has constantly a tendency to take'up more than its 

 first proportion of oxygen. Its component principles are carbon, hydrogen, azote, 

 and o.vygen. The juices oi acacia and hypocitstis, opium, liquorice-juice, the cachou, 

 &c. are extracts. Their preparation is not difficult, and may be managed, either 

 in the great way, for the purposes of extensive commerce, or in smaller trials. 



All the matters in the composition of vegetables, are reducible to these fif- 

 teen immediate principles. Before new truth and generalization had been intro- 

 duced into chemical science by the discoveries of chemistry, it was not known 

 that these principles were susceptible of analysis into others more simple. 



But the ultimate resolution of vegetables by chemical analysis, affords only 

 hydrogen, carbon, oxygen, azote, with perhaps, in most cases potash, or soda, as 

 their proper principles, and occasional contaminations of other matters in small 

 proportion. And it is not impossible, but future investigation and discovery may 

 inform us of the existence of other compounds beside those fifteen in which ve- 

 getation unites hydrogen, carbon, oxygen, and azote in peculiar modifications. 



Vegetables appear to be capable of combining the principles of carbon, 

 azote, hydrogen, and oxygen in every possible variety of proportions. 



