OF MATTER AND ITS PROPERTIES. 8 



the same impossibility of pushing the piston to the 

 farthest end of the tube; so that both water, and 

 air, and every other fluid, are equally impenetrable, 

 in this sense of the word, with the hardest body. 



By solidity, or impenetrability, in common lan- 

 guage, is sometimes understood the property of not 

 being easily separated into parts; which is better 

 expressed by the term hardness, and is very differ- 

 ent from the above meaning. 



Divisibility is that property by which matter is 

 capable of being separated into parts that can be 

 removed from eacli other. 



This divisibility is evident in bodies of a sensible 

 magnitude. Every one knows that they may be 

 divided into two, four, ten, or a thousand parts ; 

 nor can we ever, by subdividing, arrive at a part 

 so small, but we can conceive that it consists of 

 two halves. 



Matter is therefore, in imagination, infinitely 

 divisible; but it is the opinion of some philoso- 

 phers, that the actual divisibility of matter cannot 

 be carried on ad infinitum ; but that it is consti- 

 tuted of extremely minute atoms or particles, that 

 are not capable of subdivision; these ultimate 

 atoms, if they exist, must be inconceivably small; 

 nor can we by any means ever arrive at them, since 

 any one grain of the finest powder that can be 

 formed by any process consists of an immense 

 number of atoms. Some have supposed that the 

 atoms or molecules of each kind of matter were 

 created distinct from each other, and that they are 

 incapable of alteration or destruction ; a collection 

 of each forming the different elementary or simple 

 bodies. By various combinations of these simple 

 bodies, all the varieties that we see are formed. 

 b 2 



