10 THE NEW KNOWLEDGE. 



divisible, but that they consist of ultimate particles that 

 matter is no jelly but that it is made up of grains. 



We believe that, taking for example a piece of common 

 salt, if we proceeded to break it up finer and finer, we 

 should eventually, away down in the scale of fineness, 

 arrive at a piece so small, that if it were broken in two 

 we should have no longer two pieces of salt resulting, but, 

 instead, two particles widely different in their properties, 

 namely, a piece of the metal sodium and a piece of the gas 

 chlorine. This piece of salt, so small that if we broke it 

 the pieces would no longer have the properties of salt, is 

 called a molecule of salt. A pound of salt is simply x 

 molecules of salt. We believe that they move about each 

 other, under the influence of heat, as separate bodies and 

 that they are the limit beyond which it is impossible to 

 subdivide matter without destroying its identity. 



ATOMS. 



We have said that when a molecule of common salt is 

 broken down, there results a particle of sodium and a 

 particle of chlorine. These particles, the constituents of 

 molecules, are the atoms of matter. Instead, therefore, 

 of defining a compound as a substance composed of ele- 

 ments, we may say that a compound is a substance thei 

 molecules of which are made up of the atoms of the elements. ' 

 There are, of course, as many different atoms as there are 

 elements. When atoms of like kind unite together we 

 have the elements of matter, when of unlike kind the com- 

 pounds of matter. Now, since there are some seventy 

 elements, there are some seventy kinds of atoms, and when 

 we think of the varied number of combinations and per- 

 mutations, so to speak, that may be brought about by 

 tying together different numbers and different kinds of, 



