254 Prof. Daubeny on Sir H. Davy’s Theory of Volcanos. 
donment of his original views, and for his preference as a mat- 
ter of taste for others which were calculated, from their very 
vagueness, to allow full scope to that imagination, which, as 
appears from his Consolations of a Philosopher, continued in 
unimpaired vigour to the last. There is, therefore, no analogy 
between the motives of his conduct in this case and in the 
question with respect to the nature of chlorine, in which Sir 
H. Davy might feel a just pride, as having recalled the scien- 
tific world from theory to a simple expression of facts, and 
thus corrected the logic of chemistry, in quite as great a de- 
gree as he extended our knowledge of this particular class of 
combinations. 
It may be readily inferred from these remarks that I regard 
the chemical theory of volcanos, which it has been my humble 
endeavour to elucidate and to confirm, chiefly valuable by 
erecting a standard to which volcanic operations may be com- 
pared, and thus encouraging more minute attention to the 
phznomena they present. ‘This the mere vague and general 
statement of their originating in central heat is not so likely 
to do, and hence it may perhaps be regretted, if the preference 
for a simpler hypothesis, or the authority of great names, 
should so prepossess the minds of men of science as to pre- 
vent their entertaining the views I have advocated, and to 
induce them to dismiss the subject as altogether beyond the 
reach of probable conjecture *. 
It is on this latter ground chiefly that I have chosen to ad- 
dress you, for with respect to that part of the subject which 
concerns myself I should have been content perhaps to leave 
the question at issue to the candour of the public, and to the 
impression which most persons will entertain, that I at least 
can have no desire to attribute unworthy motives to Sir H. 
Davy. 
Oxford, Feb. 23, 1836. 
* In Dr. Thomson’s Outlines of Mineralogy, Geology, and Mineral Ana- 
lysis just published, I find this sentiment expressed, but the only objections 
stated to the chemical theory are, Ist, The specific gravity of the earth; 
Qndly, The nature of the elastic fluids emitted by volcanos. I regret, there- 
fore, that the learned author, who has done me the honour of quoting and 
commending the work on volcanos I published in 1826, had not zlso con- 
sulted the article on Geology in the Encyclop. Metrop., to which I contri- 
buted the portion relating to volcanos, as he would have there seen the first 
objection fully, and I hope fairly, treated, and the latter shown to be quite 
in aceordance with the theory. 
The low specific gravity of the metals of the alkalies appears to operate 
against the reception of the theory in the minds of many; yet if it can be 
shown that the bases of those volcanic products which appear upon the 
surface have collectively a greater specific gravity than the mass resulting 
from their union with oxygen, I cannot see wherein the force of this objec- 
tion resides. 
