840 Prof. Bischof on the Temperature of 



If, lastly, we suppose the carbonic acid gas to be forced into the 

 course of the water under a great hydrostatic pressure, it must 

 be immediately absorbed, and must therefore have still less 

 power to disturb, and will only disengage itself again by degrees 

 in higher regions as the hydrostatic pressure gradually de- 

 creases. 



Thus we see that the possibility of the creation of acidulous 

 springs, according to Von Buch's hypothesis, is by no means to be 

 denied. Whether all such springs originate in this manner may, 

 however, be a matter of doubt. By far the greater part only 

 exceed the mean temperature of the neighbouring fresh-water 

 springs by one or a few degrees. The origin of these cannot, 

 therefore, be very deep ; and yet the aqueous vapours, which 

 must necessarily join them in their course, in order to effect an 

 increase in their temperature, since that caused by carbonic acid 

 gas alone is scarcely perceptible, must come from a great depth. 

 In places where volcanic action still exists, the appearance of 

 fumaroles (evolutions of aqueous vapour) on the surface of 

 the earth is very frequent ; as, for instance, Italy (viz. in Tus- 

 cany), in the Lipari Islands, and so on. But is any thing 

 similar to the fumaroles to be met with in countries of extinct 

 volcanic action, in which most of the acidulous waters are found, 

 such as the neighbourhood of the Laacher See, the volcanic 

 Eifel, Bohemia, &c. .? 



It might be objected, in order to ascribe the heat of acidulous 

 springs to carbonic acid alone, that the results of my experi- 

 ments, made under the ordinary atmospheric pressure, can be 

 no criterion of the increase of temperature acquired by water in 

 the interior of the earth, where a considerable hydrostatic pres- 

 sure augments the absorption of the carbonic acid gas in a high 

 degree. It is true the increase of temperature of the water will 

 be greater the more carbonic acid gas it absorbs. But when water, 

 having absorbed five times its volume of carbonic acid gas in 

 the interior of the earth, comes to the surface, it can at the ut- 

 most retain but If its volume of free and half carbonic gas; 

 at least, that is the maximum I have found by many analyses 

 of the richest carbonated springs. The heat which the water 

 has acquired by the absorption of the carbonic acid, indepen- 

 dently of the heat of the acid itself, must, therefore, re-escape 



