THE VOLATILE PART OP PLANTS. 15 



cium, magnesium, iron, and manganese, as well as oxy- 

 gen, carbon, and nitrogen.* 



These fourteen bodies are elements, which means, in 

 chemical language, that they cannot be resolved into 

 other substances. All the varieties of vegetable and ani- 

 mal matter are compounds, are composed of and may be 

 resolved into these elements. 



The above-named elements being essential to the or- 

 ganism of every plant and animal, it is of the highest im- 

 portance to make a minute study of their properties. 



ELEMENTS OF THE VOLATILE PART OF PLANTS. 



For the sake of convenience we shall first consider the 

 elements which constitute the combustible part of plants, 

 viz. : 



Carbon, Nitrogen, Sulphur, 



Oxygen, Hydrogen, Phosphorus. 



The elements which belong exclusively to the ash will 

 be noticed in a subsequent chapter. 



Carbon, in the free state, is a solid. We are familiar 

 with it in several forms, as lamp-black, charcoal, black- 

 lead, and diamond. Notwithstanding the substances 

 just named present great diversities of appearance and 

 physical characters, they are identical in a certain chem- 

 ical sense, as by burning they all yield the same product, 

 viz. : carbonic acid gas, also called carbon dioxide. 



That carbon constitutes a large part of plants is evi- 

 dent from the fact that it remains in a tolerably pure 

 state after the incomplete burning of wood, as is illus- 

 trated in the preparation of charcoal. 



* Rarely, or to a slight extent, lithium, rubidium, iodine, bromine, 

 fluorine, barium, copper, zinc, titanium, and boron. 



