INTRODUCTION. 



SECT. II. 



PROPERTIES OF MATTER. 



15. XJODY is a substance, extended in three dimen- 

 sions, impenetrable, and moveable. 



Gravity or weight is often included in the description 

 of body ; it is left out here, because, though it ap- 

 pear to be universal, we can conceive a substance 

 without gravity, which, nevertheless, should possess 

 extension, impenetrability, and mobility. 



16. By the Impenetrability of body is meant that 

 no two particles of matter can at the same time oc- 

 cupy the same identical portion of space. 



a. If bodies could compenetrate, all matter might be 

 united into any space, however small, or it might be 

 all annihilated. MUSCHENBROEK, IntrocL ad Phil. 

 Nat vol. i. 81. 



b. The bodies that yield to pressure, and those that do 

 not, serve equally to prove the impenetrability of 

 matter. BOSCOVICH, Theoria, Phil. Nat. 41. 



17. Body, being extended, is divisible without 

 limit, or, as it is usually called, ad infmitum, sup- 

 posing that the instruments of division are mere 

 mathematical lines or points. 



a. For 



