MATTER, AND ITS GENERAL PROPERTIES. 13 



There are many instances of apparent penetration of matter, but in all of 

 ♦them the particles of the body which seem to be penetrated are merely 

 displaced. When a nail is driven into a piece of wood, the particles ol 

 wood are not penetrated, but merely displaced. If a needle be plunged into 

 a vessel of water, all the water which previously fiDed the space into which 

 It entered, will be displaced, and the level of the water in the vessel will rise 

 to the same height as it would have done, had we added a quantity of water 

 equal in volume to the bulk of the needle. "When we walk through the at- 

 mosphere, we do not penetrate into any of the particles of which the air is 

 composed, but we merely push them aside, or displace them. If we plunge 

 an inverted tumbler into a vessel of water, the air contained in it will pre- 

 vent the water from rising in the glass — and notwithstanding the amount of 

 pressure we may exert upon the tumbler, it cannot be fiUed with water until 

 the air is removed from it. 



11. By Divisibility we mean that property 

 ^sibiiity?'" "^hich raatter possesses of being divided, or 



separated into parts. 

 It has until quite recently been taught that matter was infinitely divisible; 

 that is, a body could bo separated into smaller and still smaller particles 

 without Umit. So far as our senses inform us, this is true. So long as we 

 can perceive the existence of a portion of matter by our sense of siglit, of 

 feeling, of taste, or of smell, so long we can continue to divide it. Eeyond 

 this our senses give us no information. But flie recent discoveries and inves- 

 tigations in chemistry, have proved beyond a doubt, that all bodies are ulti- 

 mately composed of exceedingly minute particles, which can not be subdi- 

 vided. 



12. To such an nltiraate portion of matter 

 ^^Atom? *^ ^^ ^^ ^^ longer separable into parts, we apply 



the term Atom. 



The extent to which matter can be divided and yet perceived 



Extent to ^j ^j^g senses is most wonderful. 



which matter ■' 



can he divid- A grain of musk has been kept freely exposed to the air of 



^' a room, of which the door and windows were constantly kept 



open, for a period of two years, during all which time the air, 

 though constantly changed, was densely impregnated Avith the odor of musk, 

 and yet at the end of that time the particle was found not to have greatly 

 diminished in weight. During all this period, ever}' particle of the atmos- 

 phere which produced the sense of odor must have contained a certain quan- 

 tity of musk. 



In the manufacture of silver-gilt wire, used for embroidery, the amount of 

 gold employed to cover a foot of wire" does not exceed the 720,000th part of 

 an ounce. The manufacturers know this to be a fact, and regulate the price 

 of their wire accordingly. But if the gold which covers one foot is the 

 '120,000th part of an ounce, the gold on an inch of the same -wire will be only 



