Chap. 4-]- [ 37 ] 



CHAP. IV. 

 VEGETABLE SUBSTANCES. 



Of the mofl remarkable Vegetable Productions. Vegetable Qxyds.* 

 Vegetable Adds.-r-Otber ejfintial Salts of Vegetables. 



IT has been already remarked, that the fimple com- 

 ponent principles, which are eflential to the forma- 

 tion of vegetable matter, are but three in number, 

 namely, carbon, hydrogen, and oxygen. From the 

 various proportions in which thefe ingredients are 

 combined, refults almoft all the variety of vegetable 

 matters which fall under our notice. Sugar, mucus 

 (under which term I include the different kinds of gums, 

 and flarch) are vegetable oxyds, having hydrogen 

 and charcoal combined, in different proportions, as 

 t.heir radicals or bales, and united with oxygen, fo as 

 to bring them to the ftate of oxyds. From the ftate 

 of oxyds they are capable of being changed into that 

 of acids, by the addition of more oxygen } and accord- 

 ing to the degrees of oxygenation, and the propor- 

 tion of hydrogen and charcoal in their bafis, they 

 form the feveral kinds of vegetable acids. On the 

 other .hand, gum by being deprived of oxygen is 

 capable of affording oil. M. Woulfe has found that 

 a pound of gum arabic diftilled with a quarter of a 

 pound of vegetable alkali, furnifhes a conliderable 

 quantity of .oil. The liquor which rifes along with 

 it is not at all acid; therefore the acid of the gum re- 

 mains united with the , alkali. Honey afforded copi- 

 oufly an oil, when fubmitted to the fame procefs. 



Pj The 



