MATTER AND FORCE. 61 



Magnetism then is a polar force; and experience 

 hints that a force of this kind may exert a certain struc- 

 tural power. It is known, for example, that iron filings 

 strewn round a magnet arrange themselves in definite 

 lines, called by some, ' magnetic curves/ and, by others, 

 Mines of magnetic force/ Over two magnets now 

 before me is spread a sheet of paper. Scattering iron 

 filings over the paper, polar force comes into play, and 

 every particle of the iron responds to that force. We 

 have a kind of architectural effort if I may use the 

 term exerted on the part of the iron filings. Here 

 then is a fact of experience which, as you will see im- 

 mediately, furnishes further material for the mind to 

 operate upon, rendering it possible to attain intellec- 

 tual clearness and repose, while speculating upon ap- 

 parently remote phenomena. 



The magnetic force has here acted upon particles 

 visible to the eye. But, as already stated, there are 

 numerous processes in nature which entirely elude the 

 eye of the body, and must be figured by the eye of the 

 mind. The processes of chemistry are examples of 

 these. Long thinking and experimenting has led 

 philosophers to conclude that matter is composed of 

 atoms from which, whether separate or in combination, 

 the whole material world is built up. The air we 

 breathe, for example, is mainly a mechanical mixture 

 of the atoms of oxygen and nitrogen. The water we 

 drink is also composed of oxygen and hydrogen. But 

 it differs from the air in this particular, that in water 

 the oxygen and hydrogen are not mechanically mixed, 

 but chemically combined. The atoms of oxygen and 

 those of hydrogen exert enormous attractions on each 

 other, so that when brought into sufficient proximity 

 they rush together with an almost incredible force to 

 form a chemical compound. But powerful as is the 



