2 OF MATTER AND ITS PROPERTIES. 



from their effects in particular states ; such as the 

 matter of heat, electricity, &c. ; and there may 

 perhaps be kinds of matter that have not yet been 

 discovered. An enumeration of all the known 

 varieties will be found under the article Chemistry. 



Every species of matter that has hitherto come 

 under our observation has been found to possess 

 the following characteristics, or properties; and, 

 therefore, we are perhaps justifiable in considering 

 them as belonging to all bodies whatever; viz. 

 solidity or impenetrability, divisibility, and mobility. 



Some species of bodies have other qualities, 

 which are not common to all; and perhaps matter 

 in general possesses properties which we are yet 

 ignorant of. 



When the terms solidity and impenetrability are 

 used to express one of the properties of matter, 

 they are not taken in the same sense as when 

 opposed to fluidity, but as that property which 

 every body possesses, of not permitting another 

 substance to occupy the same place with it at the 

 same time. If a piece of wood, or stone, occupy 

 a certain space, before you can put another body 

 into that space, you must first remove the stone, 

 or wood ; and though fluids, from their nature, 

 do not appear at first to oppose such resistance, 

 yet, in proper circumstances, they will be found 

 to possess this property in an equal degree. Put 

 some water into a tube closed at one end, and 

 insert into it a piston, or piece of wood or metal 

 that perfectly fits the inside ; you will find that 

 it will be impossible, by any pressure, to get the 

 piston to the bottom. 



If you try the same experiment with the tube 

 empty, (as it is commonly called,) but in reality 

 filled with the air of the atmosphere, you will find 



