British Association. 2am 
seated cause. And, if this be the case, the phenomenon in question 
acquires an additional interest, as affording a possible clue to the 
true nature of the processes which give rise to volcanos as well as 
to thermal springs. Now this evolution of nitrogen seems best to 
adm‘t of explanation by supposing a process of combustion to be 
going on in the interior of the globe by which oxygen may be 
abstracted from the common air which penetrates to these depths, 
whilst the residuary nitrogen is evolved. What may be the nature 
of the bodies by which this process of combustion is maintained 
must, from the depth at which the latter is carried on, be ever 
shrouded in mystery ; but it is at least certain that, whilst they 
cannot belong to the category of those which supply fuel for the 
ordinary processes of combustion of which we are ourselves eye- 
witnesses, there is nothing in the nature of the products resulting 
from voleanic action inconsistent with the idea that metals possess- 
ing a strong affinity for oxygen, but not already combined with it, 
might, if they existed in the interior of the earth, be instrumental in 
producing the supposed combustion. And, if we indulge in specu- 
lation, it may be maintained, with some show of probability, that 
the bases of the earths and alkalies which constitute the present 
crust of the globe would have existed originally uncombined with 
oxygen, and therefore must at one time have been subjected to that 
very process of oxidation and combustion which we imagine to be 
at the present time continued. The author therefore suggested that 
volcanic action may be owing to certain chemical reactions proceed- 
ing in the interior of the globe between the constituents of air and 
water, on the one hand, and the metallic bases of the earths and 
alkalies on the other. After developing this theory, the paper con- 
cluded with pointing out a practical use to which the waste waters 
of the thermal springs of Bath might be applied after they had fed 
the several baths; suggesting that, if, instead of being at once dis- 
charged into the river, they were first conveyed through under- 
ground pipes a few ‘eet beneath the surface within a given area, 
the warmth imparted to the soil would prove highly favourable to 
the culture of tender exotics, and that, if the ground were further 
protected from eold by a glass roof, a winter-garden might be 
obtained with scarcely any further expense beyond that of the 
original outlay. 
On tHe Cause oF THE ExtTRICATION OF CARBONIC-ACID FROM THE INTERIOR OF 
gun EARTH, AND ITs CHEMICAL ACTION UPON THE CONSTITUENTS OF FerL- 
spaATHic Rocks. By Dr. Daupeny, F.R.S., F.G.S., &e. 
HE author made some comments upon a theory advanced by 
Professor Bischoff, of Bonn, in his work entitled ‘Elements of 
Chemical and Physical Geology,’ in which the elevation and dislo- 
cation of certain rocks were attributed to the decomposition of fel- 
spar, through the agency of carbonic-acid, disengaged from the 
interior of the earth, seeing that the products of the decomposition 
of granite are found to possess a lower specific gravity, and there- 
fore occupy more space than the original materials of the rock. 
