340 INTERACTION OF NATURAL FORCES. 



tographs. Here compounds of silver are decomposed at the 

 place where the sun's^rays strike them. The same rays over- 

 power in the green leaves of plants the strong chemical affinity 

 of the carbon of the carbonic acid for oxygen, give back the 

 latter free to the atmosphere, and accumulate the other, in 

 combination with other bodies, as woody fibre, starch, oil, or 

 resin. These chemically active rays of the sun disappear 

 completely as soon as they encounter the green portions of the 

 plants, and hence it is that in daguerrotype images the green 

 leaves of plants appear uniformly black. Inasmuch as the 

 light coming from them does not contain the chemical rays, it 

 is unable to act upon the silver compounds. 



Hence a certain portion of force disappears from the sun- 

 light, while combustible substances are generated and accumu- 

 lated in plants ; and we can assume it as very probable, that 

 the former is the cause of the latter. I must indeed remark, 

 that we are in possession of no experiments from which we 

 might determine whether the vis viva of the sun's rays which 

 have disappeared, corresponds to the chemical forces accumu- 

 lated during the same time ; and as long as these experiments 

 are wanting, we cannot regard the stated relation as a cer- 

 tainty. If this view should prove correct, we derive from it 

 the flattering result, that all force, by means of which our bodies 

 live and move, finds its source in the purest sunlight ; and 

 hence we are all, in point of nobility, not behind the race of the 

 great monarch of China, who heretofore alone called himself 

 Son of the Sun. But it must also be conceded that our lower 

 fellow-beings, the frog and leech, share the same ethereal 

 origin, as also the whole vegetable world, and even the fuel 

 which comes to us from the ages past, as well as the youngest 

 offspring of the forest with which we heat our stoves and set 

 our machines in motion. 



You see, then, that the immense wealth of ever-changing 

 meteorological, climatic, geological, and organic processes of 

 our earth are almost wholly preserved in action by the light 



