SCIENCE OF COMMON THINGS. 



Properties of matter Impenetrability. 



vey to the mind immediate notice of some peculiar 

 action. This is the more noticeable, when we consider 

 that, however delicate its structure, each organ of 

 sense is wholly insensible to every influence except that 

 to which it is especially adapted ; thus, the eye is never 

 affected by sound, nor the ear by light. 



7 What is meant by the term body ? 



Any distinct portion of matter existing in, and oc- 

 cupying space. 



8 What do we mean, when we speak of "he properties or qualities of a 

 body? 



The powers belonging to the body, which are capa- 

 ble oif^xfeiting* In .'oiii* miad certain sensations. 



What are the general properties of matter f 



Tlu- ]a4ftdal ; qualifies of matter are MAGNITUDE or 



EXTENSION, IMPENETBABiLlTY, DIVISIBILITY, POROSITY, IN- 

 ERTIA, DENSITY, ELASTICITY, DUCTILITY, and MALLEABILITY. 



10 What is magnitude f 



The property of occupying space. It is impossible 

 to conceive of a portion of matter so minute as to have 

 no magnitude. 



11 What do we mean by the term size of a body ? 



The quantity of space a body occupies. 



13 What is the surface of a body f 



The external limits of its magnitude- 

 is What is the area of a body ? 



The quantity of surface. 



14 What is impenetrability f 



That quality of matter which precludes the possibility 

 of two bodies occupying the same space at the same 

 time. "When bodies are said to be impenetrable, it is 

 therefore meant, that one cannot pass through another 

 without displacing some, or all, of the component parts 

 of that other. 



There are many instances of apparent penetration ; but in all those, the 

 parts of the body which seem to be penetrated are only displaced. Thus, 

 if a needle be plunged into a vessel of water, all the water which pre- 

 viously filled the space into which the needle enters, will be displaced ; 

 and the level of the water will rise in the vessel to the same height as it 



