66 Dr Daubeny on Thermal Springs, 



Bakewell and Stoney-Middleton, both, according to Farey, con- 

 tiguous to that system of faults to which the heat of the Buxton 

 springs may perhaps be referred. I have also found pure, or 

 nearly pure, azote, issuing in great quantities from the tepid 

 spring called Taafe's Well, near Cardiff, in South Wales. 



lam disposed, therefore, on the strength of a. large accumu- 

 lation of facts, which might be still farther increased were the 

 inquiry extended into other parts of the globe, to consider an 

 evolution of the azotic gas, one of the most constant concomitants 

 of thermal waters, and, as such, to regard it as a phenomenon, 

 which must be kept in view, whenever we wish to offer a con 

 sistent explanation of volcanic action. 



I shall, therefore, conclude the present memoir, by applying 

 this test to the theories which appear at present to divide the 

 scientific world on the subject of volcanos, leaving of course out 

 of consideration, those attempts to explain them by the com- 

 bustion of coal, of bitumen, or of pyrites, which, however much 

 in vogue they may formerly have been, seem at present univer- 

 sally thrown aside as inadequate. Indeed Dr MacCulloch, who, 

 so far as I recollect, is the only geologist of name, that has stated 

 any specific objections to the hypothesis advocated in my work, 

 admits, at the same time, that there is no other chemical expla- 

 nation deserving of a moment's attention ; so that the question 

 reduces itself simply to a comparison between the rival claims of 

 this, and of other theories in which the phenomena are not re- 

 solved into processes of a chemical nature. 



The objections advanced by Dr MacCulloch may perhaps be 

 dismissed with the remark, that every one of them appears to 

 have been answered, as it were, by anticipation, in the 4th chap- 

 ter of my work on Volcanos, and that nearly in the order in 

 which he has propounded them ; so that I cannot help flattering 

 myself, that this geologist would find in my treatise, which, from 

 his not quoting, 1 conclude he had never seen, a solution of the 

 difficulties that have embarrassed him *. 



• Another objection I have sometimes heard advanced against the chemi- 

 cal theory, is the mean density of the earth, which is thought to be greater 

 than would be the case, if the interior consisted of the metallic bases of the 

 earths and alkalies. But those who make this objection, forget, that although 

 potassium and sodium are very light, calcium, aluminum, and wlicon are by 



