108 Afi Inquiry into the Simple Bodies of Chemistry, 



enable us to prove bodies to be compound which we now hold to be 

 simple. But even were it otherwise, we have other means of investiga- 

 tion than the processes of the laboratory, for conducting us to truths in 

 science. We have induction and analogy, without which even experi- 

 ment would fail to conduct us to the discovery of natural laws. If the 

 bodies which we term simple, present the same general physical proper- 

 ties, and exert the same chemical actions, as those which we terra com- 

 pound, and pass into the compound bodies in their characters and 

 functions, the merely negative evidence, that we are unable to decom- 

 pose them by overcoming their chemical affinities, should not invalidate 

 the conclusion, that both classes are to be placed in the same order of 

 natural bodies, and cannot be separated the one from the other, by so 

 wide a chasm as a distinct molecular constitution." 



Having enunciated his proposition, the author proceeds to the in- 

 quiry, whether, consistently with the known laws of chemical com- 

 bination, we can conceive the bodies regarded as simple to be re- 

 solvable into any other bodies more simple of their own order. He 

 makes the supposition that they may be resolved into three, having 

 the lowest atomic weight, namely, hydrogen, carbon, and oxygen. 

 He thus adopts the method of reasoning so well known, of assuming 

 certain premises, and determining their truth or error by the con- 

 clusions arrived at. This is done by a review of all the undecom- 

 posed bodies of chemistry, and of their relations with one another, 

 and with the bodies which we know to be compound. The results 

 are in many cases remarkable, but in no case, as far as we can per- 

 ceive, inconsistent with the laws of chemical combination, as deter- 

 mined by experiment. 



But of the three bodies referred to, one or more may be com- 

 pound. Pursuing the same mode of reasoning, one of them is as- 

 sumed to be compound, and this one to be oxygen ; because, while 

 the known atomic weights of hydrogen and carbon, 1 and 6 respec- 

 tively, will allow us to suppose one or both to be resolvable into 

 oxygen, the atomic weight of oxygen, 8, will not allow us to resolve 

 oxygen into hydrogen or carbon. This is the second stage of the 

 argument, although carried on coincidently with the first. The 

 author, therefore, makes' the supposition, that all the undecomposed 

 bodies may be resolvable into two of their own order, namely, hydro- 

 gen and carbon ; and this supposition is to be tested, like the other, 

 by its accordance or disagreement with the results arrived at. It is 

 remarkable, that this stage of the hypothesis, though arrived at by 

 a different train of reasoning, agrees with a favourite speculation of 

 Sir Humphrey Davy, who supposed that all the simple bodies of 



