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negatively electrified. A second class suppose the 

 efitcts to be produced by two different fluids, called 

 by them the vitreous fluid and the resinous fluid ; and 

 others regard them as affections or motions of matter, 

 or an exhibition of attractive powers, similar to those 

 which produce chemical combination and decomposi- 

 tion ; but usually exerting their action on masses. 



The different powers that have been thus gener- 

 ally described, continually act upon common matter 

 so as to change its form and produce arrangements 

 fitted for the purposes of life. Bodies are either sim- 

 ple or compound. A body is said to be simple, when 

 it is incapable of being resolved into any other fbrms 

 of matter. Thus gold, or silver, though they may 

 be melted by heat or dissolved in corrosive menstrua, 

 yet are recovered unchanged in their properties, and 

 they are said to be simple bodies. A body is consi- 

 dered as compound, when two or more distinct sub- 

 stances are capable of being produced from it ; thus 

 marble is a compound body, for by a strong heat, it is 

 converted into lime, and an elastic fluid is disengaged 

 in the process : and the proof of our knowledge of 

 the true composition of a body is, that it is capable of 

 being reproduced by the same substances as those into 

 which it had been decomposed ; thus by exposing 

 lime for a long while to the elastic fluid, disengaged 

 during its calcination, it becomes converted into a sub- 

 stance similar to powdered marble. The term element 

 has the same meaning as simple or undecompounded 

 body ; but it is applied merely with reference to the 

 present state of chemical knowledge. It is probable., 



