744 Meeting of the British Association. [Oct., 
that there was ample reason to infer that the evolution of nitrogen gas 
when in great excess of the oxygen was essentially connected with that 
igneous action which is going on in the interior of the earth, and that 
it was met with in thermal waters only because the latter derived their 
heat from the same chemical operations which give rise to the phe- 
nomena of volcanoes. We are thus compelled to assume that some 
process of oxidation is going on in the locality, such as should bring 
about the absorption of the oxygen present in the air which penetrates 
to these depths. The author then entered into a most interesting 
discussion as to the cause of thermal springs and volcanoes; the latter 
phenomena especially resembling those which would oceur if water 
and air were brought into contact with metallic bases possessing a 
strong affinity for oxygen; and concluded by suggesting that the 
surplus heat from the springs, which was at present allowed to be 
wasted in the river, should be utilized by allowing the water to pass 
through coils of pipes let into the ground a few feet below the surface, 
so as to communicate its heat to the soil within a given area. With 
no further expense than this, such an arrangement would secure to the 
plot of ground placed under the influence of this adventitious tem- 
perature a bottom heat sufficient for the growth of early vegetables 
and for the cultivation of tender exotics; whilst if the waters were in 
the first instance emptied into a small pond, and afterwards transmitted 
from thence by means of a coil of pipes gradually embracing a larger 
circle as they extended, nothing but the protection of an external 
covering of glass would be required for the cultivation of the gigantic 
Victoria Regia and other tropical water-lilies; whilst the borders of the 
pond would at least secure to the inhabitants of Bath the enjoyment of 
many of the trees and shrubs of warmer countries in the open ground 
of the garden, and a participation in a genial atmosphere during their 
most rigorous seasons. 
The Gun-cotton Committee laid their second report before the 
members of this Section. This was merely a formal document relating 
the circumstances which have taken the matter out of their hands. | 
The Government have appointed a committee to investigate the subject 
in all its bearings, and have placed on it several members of the British 
Association Committee. At the close of the report, Professor Abel 
said that his researches, made on behalf of the Government, were of a 
satisfactory character, gun-cotton possessing a great superiority over 
gunpowder both in the simplicity and safety of its manufacture. 
Dr. Miller then read a paper, “On the Wheal Clifford Hot Spring, 
near Redruth, Cornwall,” in which he had detected so large a quantity 
of Lithium that it could not fail to become an economical and abundant 
source of that rare alkaline metal. 
Mr. A. Poole King read a paper, “On the Premature Decay of the 
Frescoes in the Houses of Parliament,” in which he predicted the 
rapid destruction of these frescoes if the apartment were allowed to 
remain cold and damp. The moisture would condense in drops on its 
surface, and be absorbed. These drops would dissolve whatever trace 
