Natural History of Volcanos and Earthquakes. 71 
be the Neptunian formations, is an argument in favor of these — 
springs deriving their ingredients principally from the basalt. 
_ The organic matter found in such abundance in the sulphure- 
ous springs of the Pyrenées (baregine, glairine, animal matter) 
proves, that their chemical constituents must be derived, at least 
in part, from the Neptunian formations. Since no carbonic acid 
escapes from the rocks there, the granite in the interior may, in- 
deed, suffer but slight decompositions. The formation of the sul- 
phureous springs there, probably by the decomposition of sul- 
phates by organic matter, is certainly much favored by the high 
temperature of these springs; and this again is a consequence of 
the great depth to which the clefts extend in the strata, which 
are piled up one on another in considerable masses, and partly 
raised up, With many strata-surfaces between them. The coin- 
cidence of various circumstances may thus produce one class of 
thermal springs in preference to another. : 
In the Alps, where, on account of the absence of escapes of 
carbonic acid gas, decompasition of the granite and other vol- 
canic rocks does not take place, and where even the Neptunian 
formations contain few soluble substances, we find thermal 
springs, which are scarcely any thing more than ordinary warm 
Water, 
On the other hand, we see thermal springs issuing, to all ap- 
Peatance, from erupted masses, which springs contain ingredients 
*pparently peculiar to those which can be proved to issue from 
Neptunian formations. This is, for instance the case with the 
Salt-spring, which rises at Kreuznach out of porphyry. This 
Tock is but little fissured, and yet the high temperature of the 
“rings, 58° to 83°, indicates a deep origin. Since the porphyry 
has penetrated the variegated sandstone, the latter, and also the 
shelly limestone, lie in close contact with the springs, so that this 
Voleani¢e rock has no other share in the formation of these springs, 
an the production of deep clefts between itself and the Neptu- 
nian formations, which have permitted meteoric water to penetrate 
Into the strata containing the salts. We must not pass over one 
*ireumstance, which induces us to attribute to these saline springs 
* totally distinct origin, viz., that sulphate of lime, which other- 
Wise so generally accompanies the common salt, is here entirely 
absent, and that these springs are remarkable for their abundance 
of bromine and iodine. 
Ree Ree ORS © ent 
