165 
compose, say, these very Bath Waters, how are they taken up by 
the rain water in its passage through the earth? Looking at 
this table of analysis, I find that there are present Calcium, 
Magnesium, Sodium, Potassium, Sulphuric Acid, Silicie Acid, 
Carbonic Acid and Chlorine, also Strontium, Lithium and Iron 
in small quantities. Now, we can account for Sodium, Potassium 
and Lithium being present, for nearly all the salts of these metals 
are soluble ; but with regard to the Magnesium, Iron, Silicic Acid 
and Carbonic Acid, how are we to account for their presence ? 
We may reasonably suppose that some of the rain water penetrates 
to a very great depth, owing either to crevices, or the permeable 
nature of the strata through which it passes. These waters 
would, naturally, have the same temperature as the earth around 
them. Calculating the downward increase of temperature at 
about 1° Fahrt. for every 55 feet, at the depth of two and 
a half miles we should find a heat some 30 degrees over boiling 
point ; and I think it is a question for consideration, whether the 
action of water, under high temperature and pressure on car- 
bonaceous residue, might not account for the large quantity of 
Carbonic Acid gas given off by Mineral Springs. Again, another 
theory I submit to your notice ; May not the internal heat of the 
earth have some decomposing action on the lower lying limestones? 
It is a known fact, that at a low red heat (more especially if in 
the presence of carbonaceous matters) Limestone will commence 
giving off Carbonic Acid gas. 
I lay great stress on this gas question, for if we can satisfactorily 
account for its presence, then the case of the other metals is easily 
settled, as I will explain. It has been demonstrated by Chemical 
experiment, that many Siliceous rocks were decomposed when 
exposed to the action of water saturated with Carbonic Acid gas 
at considerable pressure ; and that the substances dissolved by 
such water, corresponded with the various contents of many 
mineral springs. It is also a known fact that water vapour at 
___ high temperature will dissolve Silica. The source of the Nitrogen 
