NATURE OF CHEMICAL AFFINITY 



heat and electricity. This is especially the case with 

 the action described under (2) and (3). In a similar 

 manner chemical changes are dependent usually upon 

 the action of heat and electricity. These relations 

 and the nature of chemical affinity may be to some 

 extent explained as follows : 



" The atoms of all ponderable matter are in con- 

 stant motion. Upon the rapidity and extent of this 

 motion depend its physical condition, whether it is 

 to be solid, liquid, or gaseous. Every force which 

 alters the vibrations of the atom must also change 

 the properties of the matter, since these properties 

 depend upon the movement of the atoms. Besides 

 ponderable matter, there exists the imponderable ether, 

 whose atoms are in continuous motion and whose 

 vibrations produce the phenomena of heat, light and 

 electricity. These vibrations can transplant them- 

 selves as such into the atoms of ponderable matter, 

 and thereby cause a change in the nature of the molec- 

 ules, thus producing chemical action. For instance, 

 when light falls upon Silver Chloride, the latter be- 

 comes black, and a part of the light as such, disap- 

 pears. This is because the rapid vibrations of the 

 Ether are transformed into slower vibrations which 

 they share with those of the material atom, and which 

 manifests itself by the decomposition of the Silver 

 Chloride. In other instances, the character of the vibra- 



181 



