THE VOLATILE PART OF 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- 

 pof tance to make a minute study of their properties. 



§2- 



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, cbarcoal, 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; 



•-•JEarely, or to a alight extent,. lithium, rubidium, iodine, bromine, 

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



