738 Meeting of the British Association. [Oct., 
contents. Sir Charles believes that the efficacy of the new metals for 
medicinal purposes will probably soon become manifest, and that they 
will be produced in large quantities and employed in the cure of 
diseases “which have hitherto baffled human skill.” 
After noticing some of the phenomena connected with the gradual 
decrease of temperature in the water as it rises in hot springs and the 
minerals with which it is charged, he expresses the belief that there 
is some relationship ‘“‘ between the action of thermal waters and the 
filling of rents with metallic ores,” suggesting that the component 
elements of the ores may first be held in a state of solution or sub- 
limation in the intensely hot water below, and as this cools be deposited 
in the fissures. 
Another geological phenomenon in which he believes hot springs 
to play a prominent part is metamorphism, the conversion of deposited 
strata, many of which once were full of organic remains, into crystalline 
rocks. Recent experiments and observations have taught geologists that 
such changes have been the result, not of heat alone, but of heat and 
water combined, of “ hydrothermal” action ; that such rocks have been 
converted, not in the “dry way,” which would necessitate an enormous 
amount of heat, but in the “ wet way,” “a process requiring a far less 
intense degree of heat.” 
Adducing as evidence the experiments of Senarmont, Dobree, 
Sorby, Sterry Hunt, and other reliable observers, as well as that 
afforded by the action of thermal springs during the historic period, 
Sir Charles believes that in the course of ages whole mountain masses 
may have become thus converted, by means of water permeating 
through them charged with carbonic and hydrofluoric acids. Whilst, 
however, he is disposed to substitute for intense heat a longer period’ 
of time for the formation of crystalline rocks, Sir Charles still holds 
that the temperature of the mass below, with which the water is mixed 
up must be extremely high, and referring to the experiments of Bunsen 
on the Great Geyser of Iceland, he mentions that at a depth of only 
74 feet water in a state of rest possesses a temperature of 248° Fahr. ; 
the temperature then at a depth of a couple of thousand feet is probably 
intense, as the erupted glowing lava of volcanoes testifies. 
To account for this increasing heat as we descend into the earth is 
at present impossible, or, as Sir Charles observes, “the exact nature 
of the chemical changes which hydrothermal action may effect in the 
earth’s interior will long remain obscure to us, because the regions 
where they take place are inaccessible to man; but the manner in 
which volcanoes have shifted their position throughout a vast series of 
geological epochs—becoming extinct in one region and breaking out 
in another—may perhaps explain the increase of heat as we descend 
towards the interior, without the necessity of our appealing to an 
original central heat or the igneous fluidity of the earth’s nucleus.” 
Quitting then the subject of hot springs, the President adverts to 
the changes which, in past ages, have taken place in the land-level of 
England, and refers to the time when “the Cotswold Hills, at the foot 
of which this city” (Bath) “is built, formed one of the numerous 
islands in an archipelago into which England, Ireland, and Scotland 
