22 Sir C. Lyell on the Mineral Waters of Bath. 
waters being exceptional. Nevertheless, there is a ee 
sumption that there exists some relationship between the a 
of thermal waters and the filling of rents with metallic o 
The component elements of these ores may, in the first instane 
rise from great depths in a state of sublimation or of solution i 
intensely heated water, and may then be precipitated on» 
walls of a fissure as soon as the wee vapors or fluids be 
fen before the spring reaches the earth’s Bi ti Tf this the 
be adopted, it will follow that the metalliferous portion of a 
sure, originally thousands of feet or fathoms deep, will never 
exposed in regions accessible to the miner until it has been Up 
heaved a long series of convulsions, and until the highe 
parts of the same rent, together with its ‘contents and the To 
which it had traversed, have been removed by aqueous denuda 
- tion. es before such changes are APP HEE, thermal an 
mineral springs will have ceased to act; so that the want @ 
identity between the mineral feeestaicuts of hot springs and th 
contents of metalliferous veins, instead of militating ne the 
intimate relationship, is in favor of their being me plemen- 
tary results of one and the same natural operation 
apna there are other characters in the structure "of the oon 
Strata of Ahn gins many of them once full of organic fr 
mains, have been rendered Percnly or wholly erystalline. 
is admitted on all hands that heat has been instrumental 
bringing about this re-arrangement of particles, which, when ta 
metamorphism has been carried out to its fullest extent, obli 
ates all trace of the imbedded fossils. But as mountain-m¢ 
many miles in length and breadth, and several thousands of feet 
in height, have undergone such | caltarect it has always beet 
difficult to explain in what manner an amount of heat capabl 
carbonic acid and with fluohydric acid (which last is often pret 
ent in small qUABE SE), are powerful causes of decom: tio: 
and chemical reaction in rocks through which they 
3 way a proc 
a rina heat. Thermal springs, pres 
