Sir 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 be 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 
vy’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 thé 
conclusion in question, is that calomel is a compound of protoxide of 
mercury and muriatic acid: but no, you say, itis @ compound of 
chlorine and metallic mercury.t-—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 thlorine of the 
muriatic acid united with the metallic part of the oxide of tin, while 
the hydrogen of the acid united with the oxygen of the metal to feta 
* Nich. Journal, XXX. 29. ¢ See Murray’s Elements, 6th edition, Appendix. 
