90 COMPOUND ORGANS OF PLANTS. 



and Johnson, and we are about to lay before the student the 

 results of the labors of these philosophers. 



The solid part of plants, chemically considered, is found to 

 consist of organic and inorganic matter ; the first may be burnt 

 away and is derived from the atmosphere, the second is incom- 

 bustible and is derived from the soil in which the plant grows. 



To show the organic and inorganic matter in plants. Burn 

 a piece of wood or straw. in the flame of a lamp. The part 

 which burns is organic matter and passes again into the atmo- 

 sphere from whence it was taken; the incombustible ash that 

 remains is the inorganic matter in the plant, which was derived 

 from the soil. 



The organic part of plants is composed of four substances, 

 carbon, or charcoal, more than one-h&,lf, oxygen one-third, 

 hydrogen one-twentieth, and nitrogen one-fiftieth. 



The inorganic part of plants, or the ash remaining after the 

 combustion of the organic matter in them, consists of no less 

 than eleven different substances, viz : potash, soda, lime, mag- 

 nesia, silica, oxide of iron, oxide of manganese, sulphur, sul- 

 phuric acid, phosphoric acid, and chlorine. 



The carbon or charcoal in plants composes more than one- 

 half of their entire bulk. If a green leaf or a piece of wood 

 be charred (which may be done by heating it in a close vessel 

 out of contact with the air,) all the hydrogen and oxygen in 

 the plant will be driven off, and what remains will be the 

 amount of carbon in the plant, together with a small per- 

 centage of inorganic matter. The leaf or specimen of wood 

 which has been thus carbonized will be found to preserve its 

 form and bulk uninjured, even to that of the most delicate 

 cells and vessels, but will be considerably lighter. A piece oi 

 common stove charcoal is a beautiful instance of wood which 



