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, K, Fig. 2, are 



Fig. 2. 



inclined from the erupted volcanic mass B, 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 pressurg 

 exerted at so great a 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- 

 bonic acid and carbonates. The deeper the meteoric water pen- 

 etrates, the warmer it becomes. Risinu; springs of water are 

 then produced in this cleft, through which the concentrated min- 

 eral water formed beneath at c, rises to b. 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 ah e, or runs at a slight depth below the 

 surface, then the mineral spring will issue, owing to the pressure 

 of the column of water a b. While the rising streams of warm 

 water take tlie course c 6 ri, 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 dnninished, and thus free carbonic acid 

 gas is evolved at d with the acidulous spring. It is 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 h d, but Alls all the intervals 



