MEMOIR XL] THE FORCE INCLUDED IN PLANTS. 



pages : " Whence has the force which manifests itself as 

 heat and light in a flame been derived? Force cannot 

 be created ; it cannot spring forth spontaneously out of 

 nothing." 



The answer is, it came from THE SUN. 



Under the influence of his rays the growing plant de- 

 composed carbonic acid obtained from the atmosphere, 

 appropriating its carbon and setting its oxygen free. To 

 accomplish this decomposition, this appropriation, it was 

 necessary that a portion of the energy contained in those 

 rays should be absorbed. Associated with this, the car- 

 bon could now form part of the plant, and, indeed, con- 

 stituted the solid basis of which it was composed. 



But the force thus associated with the carbon atoms 

 was not annihilated ; it was only concealed : through 

 countless ages it might remain in this latent state, ready 

 at any moment to come forth. All that is requisite is 

 to oxidize the carbon, to turn it into carbonic acid, and 

 the associated energy, under the form of heat and light, 

 is set free. 



When we read by gas or by the rays of a petroleum 

 lamp, the light we use was derived from the sun perhaps 

 millions of years ago. The plants of those ancient days, 

 acting, as plants do now, under the influence of sunshine, 

 separated carbon from the carbonic acid of the atmos- 

 phere by associating it with the radiant energy they had 

 absorbed, and this remained for an indefinite time en- 

 closed, as it were, in the now combustible material, ready 

 to be disengaged as soon as the reverse action, oxidation, 

 takes place, returning then to commingle as heat with 

 the active forces of the world. 



Much of what has here been said applies to hydrogen 

 as well as to carbon. Hydrogen is derived, under similar 

 conditions, from the decomposition of water or ammonia. 

 When its oxidation recurs, it delivers up, under the form 



