in Reply to Dr. John Davy. 253 
pounded by Cordier, even of the water and the muriatic acid, 
which are noticed by Davy himself as issuing from the vol- 
cano, whose phenomena he describes. 
Whatever ground, therefore, may exist for his scepticism 
on the subject, none certainly has been assigned for his 
adoption of the rival hypothesis, which, without effecting the 
object of explaining the facts, is saddled with assumptions 
equally gratuitous ; the existence of the alkaline and earthy 
bases in the interior of the earth, being not more unsupported 
by direct evidence, than that of a central fluid mass; seeing 
that the increasing temperature detected in descending into 
the bowels of the earth, may be explained quite as well by 
chemical processes carried on at the requisite depths, as by 
the hypothesis of central fluidity. 
I trust I have now said enough to justify my having stated 
that Sir Humphry only gave his zpse dixif in support of his 
new hypothesis, a point which I was at that time more parti- 
cularly anxious to establish, from a wish to obtain for the 
theory I had advocated an unprejudiced hearing, and being 
well aware of the weight which the deliberate judgement of 
such an authority as that of Sir H. Davy on a question of 
science would obtain with most readers. Since that time the 
favourable opinion expressed by the present as well as by the 
late President of the Geological Society with respect to the 
chemical theory, will have secured it a candid reception 
amongst naturalists; whilst the authority of one of the most 
distinguished of Sir Humphry Davy’s living cotemporaries 
and rivals in science, Mons. Ampére, will vindicate its claim 
to respect amongst chemical philosophers.—One more word 
with respect to the reasonableness of imagining that Davy 
might choose to abandon his former hypothesis without deli- 
berate consideration. 
In the first place, considering the numberless applications 
of which his great discovery of the alkaline and earthy bases 
admitted, it is not necessary to suppose that he would regard 
this one with any peculiar favour. And indeed the only al- 
lusion I find to it at all in any of his earlier publications con- 
sists of four lines in a note appended to his Memoir on the 
Decomposition of the Earths. 
Secondly, the solid character of the discoveries on which 
the reputation of Davy was based, would naturally make him 
indifferent as to the fate of a theory resting on assumptions 
which, whether probable or not, were such as could themselves 
neither be substantiated nor set aside by direct experiment. 
The higher, indeed, we estimate the fame of Sir H. Davy, 
the less difficult will it appear to us to account for his aban- 
