4 
64 Natural History of Volcanos and Earthquakes. 
never, flow out at the boundary between the erupted masses and 
the fundamental rocks, gives us an indication where to seek their 
origin. If the strata of the fundamental rocks, A, A, Fig. 2, are 
: Fig. 2. 
inclined from the erupted volcanic mass RB, then a cleft will be 
formed to a great depth in the interior of the earth at the boun- 
dary between this cone and the fundamental rocks, in conse- 
quence of the contraction of the former during its cooling. Down 
this cleft the meteoric water penetrates and meets the streams of 
carbonic acid gas developed in the interior. ‘This latter is ab- 
sorbed by the water, owing to the strong hydrostatic pressure 
exerted at so greata depth. This forms a water impregnated 
with carbonic acid, which effects a decomposition and solution 
of the stone, and hence arises an acidulous spring, rich in car- 
bonie acid and carbonates. The deeper the meteoric water pen- 
etrates, the warmer it becomes. Rising springs of water are 
then produced in this cleft, through which the concentrated min- 
eral water formed beneath at ¢, rises to 6. If here the direction 
of the slaty or stratified surface (Schieferungs oder Schichtungs 
Flache) leads down to d, which either has an immediate exit in 
the section of the valley abe, or runs at a slight depth below the 
surface, then the mineral spring will issue, owing to the pressnre 
of the column of water ab. While the rising streams of warm 
water take the course céd, the originally concentrated mineral 
water becomes diluted by the fresh water flowing down from 
above ; the carbonic acid gas, absorbed in great quantity beneath, 
is gradually disengaged as the water rises, and consequently the 
hydrostatic pressure is diminished, and thus free carbonic acid 
gas is evolved at d with the acidulous spring. It 1s clear, that 
the carbonic acid gas, which is constantly disengaged from the 
rising water during its whole course, not only moves on with the 
water on the surface of the stratum 6d, but fills all the intervals 
‘a 
