(Sm- Humphry Davy. 235 



ment was essential to the success of the experiment) a triple com- 

 pound, as in olefiant gas.* This argument, if it did not demonstrate 

 that the carbonic acid was developed in this manner, proved at least 

 that it might he thus accounted for, and thus rendered Murray's ex- 

 periment inconclusive ; but a subsequent experiment of Dr. Davy de- 

 veloped a new compound formed from these elements, which Murray 

 had mixed, namely, chloro-carbonous acid, which was the substance 

 that Murray had mistaken for carbonic acid. 



Again, Davy asserted a superiority in favor of his doctrine, on the 

 ground that it was only a simple expression of facts, while that of his 

 antagonist, was an hypothesis. Thus, to say that muriatic acid is 

 composed of chlorine and hydrogen, was only the expression of a 

 simple fact, which we saw take place before our eyes ; while the 

 assertion that the hydrogen unites with the oxygen of the chlorine and 

 forms water, which instantly combines with the muriatic acid, is hy- 

 pothetical. All this seemed very clear, until Murray shewed that 

 Davy's views were as hypothetical as his. For, although to assert 

 that from the mutual action of oxymuriatic acid and hydrogen, mu- 

 riatic acid is produced, is a simple expression of a fact, yet that this fact 

 results from a direct combination of those two gases is an inference, 

 and that it results from the union of the hydrogen with the oxygen of 

 the oxymuriatic acid, is another inference. And, though the latter 

 inference may be less simple than the former, yet the most simple 

 conclusion is not always the just one. This observation was pressed 

 home by an appeal to their own principles. For example, we com- 

 bine (says Murray) protoxide of mercury with muriatic acid and form 

 calomel. The most simple conclusion, and one quite analogous to the 

 conclusion in question, is that calomel is a compound of protoxide of 

 mercury and muriatic acid : but no, you say, it is a compound of 

 chlorine and metallic mercury.f — This was a pungent application of 

 the argumentum ad hominem. — The dexterity of the combatants was 

 equally manifested on another point. When muriatic acid was com- 

 bined with a metallic oxide, as oxide of tin, a quantity of water made 

 its appearance, and a compound resulted, the same as that which is 

 formed by the direct combination of chlorine and metallic tin. From 

 this experiment, Davy drew the inference, that the chlorine of the 

 muriatic acid united with the metallic part of the oxide of tin, while 

 the hydrogen of the acid united widi the oxygen of the metal to form 



^ Nich. Journal, XXX. 29. + See Murray's Elements, 6th edition, Appendix. 



