18 Sir C. Lyell on the Mineral Waters of Bath. 
of the earth at some former period—perhaps not a very rem 
one, geologically speaking. The uppermost part of the rent — 
through which the hot water rises is situated in horizontal strata — 
of Lias, and ‘Trias, 300 feet thick; and this may be more m 
ern than the lower part, which passes through the inclined and © 
broken strata of the subjacent Coal-measures, which are uncon- — 
formable to the Trias. The nature and succession of these rocks — 
grains of salt, or chlorid of sodium, to 4 of the chlorid of 
magnesium. That some mineral springs, however, may derive — 
an inexhaustible supply through rents and porous rocks, from 
the leaky bed of the ocean, is by no means an unreasonable the- 
ory, especially if we believe that the contiguity of nearly all — 
the active volcanos to the sea is connected with the access 
salt water to the subterranean foci of voleanic heat. 
last few years by what is called spectrum analysis. By this n 
method, the presence of infinitesimal quantities, such as would 
