18 INTRODUCTION. 



earth contains at least nine, and each of these is again complex, con- 

 taining for one principle, oxygen, the same that exists both in wa- 

 ter and in the atmosphere, united to nine or ten varieties of met- 

 als or combustibles none of which are known in common life. 



He who is acquainted with the wonderful effects of chemical com- 

 bination, will not think it strange that half the weight of marble is 

 carbonic acid, and that metals, when combined with oxygen, resemble, 

 very exactly, the earthy substances. 



Light as well as heat, is contained in common fire, and therefore 

 it is not simple, unless fire and heat are varieties of one and the same 

 thing. 



Modern research has proved that, besides light, which in its 

 seven prismatic colors, is contained in the solar beam, there is also, 

 in this emanation, an opake, radiant principle, which accompanying 

 light and heat, neither warms nor illuminates, but acts to decompose 

 certain chemical compounds ; that there are opake rays which warm 

 but do not illuminate, and illuminating rays which are cold to the 

 sense of living animals, but impart to the universe its splendid drape- 

 ry of colors ; and that, associated with one or more -of these emana- 

 tions, there is a surprising power, which imparts magnetism to a needle, 

 and gives it the properties of the loadstone. But we have used the 

 word element without defining it. 



An element is an undecomposable body it is therefore simple, or 

 in other words not reducible to any other form of existence. We 

 must however, carefully distinguish, between real elements, and those 

 which are such, only in relation to the present state of our knowledge. 

 When modern science speaks of a body as elementary, it intends 

 nothing more, than that it has not been decomposed. It is therefore 

 simple as far as we know, but it is possible that, by future efforts, it 

 may be decomposed. Although we have no reason to doubt, that 

 there are real elements, we cannot say, that we are certainly in pos- 

 session of any one element. It is, however, perfectly safe to 

 reason upon bodies as elementary, until they are proved to be 

 compound. Iron is, as far as we know, a simple body ; we cannot 

 as yet, exhibit it In any simpler form ; all we can do, is to alter 

 its figure and size, without at all changing its nature. But iron 

 rust, or the scales which fly off, when red hot iron is hammered, are 

 not simple ; they consist of iron, combined with oxygen, one of the 

 principles of the atmosphere ; we can exhibit these substances in a 

 simpler form; the iron, which they contain can be separated from 

 the aerial principle, and both can be exhibited apart, and thus the 

 proof will be complete ; red lead and red precipitate are still better 

 examples, because the former can be partially, and the latter wholly, 

 brought back to the condition of metals, by simply heating them. 



