24 CHEMISTRY. 



serve to impress upon your minds more strongly some of 

 the great principles and facts of chemistry. 



20. Molecules. The atomic philosophy assumes that mat- 

 ter can not be infinitely divided that is, you may cut and 

 pulverize any thing as fine as you please, and you may then 

 think the smallest attainable particles divided again and 

 again, smaller and smaller, until you reach a certain limit, 

 beyond which matter can not be subdivided. Hence bod- 

 ies consist of an immense number of little particles called 

 molecules literally, little masses. These molecules do not 

 touch each other, but are separated by empty spaces, and 

 these void spaces are very large compared with the dimen- 

 sions of the molecules themselves. These little particles 

 are held near each other by some force, or attraction, as it is 

 often called, and this force varies considerably in power in 

 the three different states of matter with which you are fa- 

 miliar. It is supposed that if it were not for the fact that 

 these molecules do not touch each other, we would be un- 

 able to cut any substance into pieces, for the small parti- 

 cles of matter are considered to be impenetrable ; and when 

 a knife-edge is forced into a body, it simply enters the void 

 spaces between the molecules and makes them separate it 

 does not penetrate the substance of the molecules them- 

 selves. It seems strange at first to think of hard substances 

 like iron and silver as made up of particles which do not 

 touch each other; but this is a way of regarding them which 

 you will find easier to accept the longer you study. Do not 

 for an instant think that these little particles are ever visible 

 to any one, even with the aid of a most powerful microscope. 

 They are so small that we can only think them. "What we 

 do see are immense numbers of these molecules aggregated. 

 To give you a faint idea of the littleness of these particles, 

 we will tell you that philosophers have conjectured that fifty 

 million million molecules placed in a row would occupy the 



