64 THE CULTURE OF FARM CROPfe. 



of sources. It is given off copiously by the lungs of ani- 

 mals during respiration: it is formed during the process of 

 fermentation, and the decomposition of all organic sub- 

 stances. But its absorption and reproduction in nature 

 seem to be perfectly balanced. It exists primarily in the 

 air to the extent named and is equally diffused throughout 

 the mass of it. Plants spring up and grow and form their 

 substance by its absorption from the atmosphere both di- 

 rectly and through the water which dissolves it. Plants de- 

 cay and return their carbonic acid to the atmosphere. 

 Animals feed upon the vegetation, convert the carbon into 

 carbonic acid in their system by the production of vital 

 heat, which is a true process of combustion ; and exhale the 

 gas from their lungs. Men dig coal from the bowels of the 

 earth or cut timber from the forests and use these for fuel ;. 

 in the combustion enormous quantities of carbon stored up 

 in these substances are changed into carbonic acid, and are 

 discharged into the air, in which it is immediately diffused. 

 The succeeding generations of plants take this new supply 

 and convert it to their uses and thus a grand routine is 

 completed and the precise balance is maintained. This is 

 but one of the many beautiful instances of the operation 

 of a set of natural laws, the effects of which produce what 

 is called the balance of nature; or the conservation of force. 

 Both of these terms are well applied, and strictly correct, 

 for as every operation of nature consumes force, it is the 

 balance of these forces which maintains the equilibrium of 

 the universe, preserving order and regularity of motion, 

 which goes on undisturbed as generations come and go and 

 centuries roll around; typifying tile eternity of matter and 

 the indestructible nature of elements. 



