n.y||L|j iiiii.yiijiflwppippw'; 



4# 



OF CARBON. 



Woody fibre contains 38 per cent of carbo;i, 



Meadow hay contains 44 per cent of carbon.* 



Tlie analysis of vegetable oils, such as olive 

 or linseed oil yields carbon 77 parts. 



In all these analyses water is stated instead 

 of its component parts of oxygen and hydro- 

 gen, this is done to simplify the subject under 

 consideration; but the analysis of water will 

 be considered in its due and proper place. 



From these results it must be apparent that 

 a due supply of carbon is absolutely necessary 

 to vegetable life, and to enable plants to create 

 such substances as sugar, starch, mucilage and 

 oils. From whence that supply is obtained 

 will now form the next subject for our conside- 

 ration. 



" Vegetable physiologists have hitherto con- 

 sidered the fertility of every soil to depend on 

 the presence of a substance called humus. This 

 substance, hitherto recognised as the nutriment 

 of plants and believed to be extracted by them 

 from the soil in which they grow, is itself the 

 product of the decay of other plants." 



" It has been called by a variety of names, 

 such as humus, humic acid, coal of humus, &c. 

 according to the external characters each spe- 

 cies has presented, and hitherto the opinion, 

 that this substance humus is united in some 

 way or other with the carbon, has been so pre- 

 valent as to seem to require no argument in its 

 favour." 



"The obvious difference in the growth of 

 plants, according as the soil contained a greater 



* Liebig. 



