260 M. Bischof on the Subterranean Course of Water, 



I have examined in the neighboiu-hood of the Laacher-See. 

 None of these last can overcome the force of a column of water 

 more than 5 inches high ; while, as I found, the gas streaming 

 out at Meinberg overcame with ease the pressure of a column 

 of water 12 inches high, and could without doubt have over- 

 come a column of water several feet high. This comparatively 

 considerable expansive force of the streaming out gas, induces us 

 to believe that it comes as gas from its source, without having 

 been absorbed by water ; for gas which is disengaged from the 

 water, by which it had been absorbed, in consequence of the di- 

 minution of the hydrostatic pressure during the progress to the 

 surface, can naturally have an expansive power only equal to, 

 or very slightly exceeding, that of the pressure of the external 

 air. 



Those who explain the ascent of mineral springs by the ope- 

 ration of the pressure which the water suffers from the carbonic 

 acid gas generated in the subterranean laboratory, do not reflect 

 that the regularity in the pouring out of the spring is irrecon- 

 eilable with that supposition. I have had many opportunities 

 of observing mineral waters, which are rich in carbonic acid gas, 

 uninteiTuptedly at different periods of the day and year, and 

 have always observed a singular regularity in the springing out 

 and flowing off" of the water, and in the disengagement of the 

 carbonic acid gas. The latter issued from the mineral springs 

 abounding in carbonic acid in uninterrupted streams, so thai 

 the whole spring seemed to be in a state of ebullition ; while from 

 the springs having less carbonic acid, the gas ascended either in 

 innumerable small bubbles, or periodically in single larger ones. 

 Otherwise the size of the bubbles is regulated by the nature of 

 the ground ; if the spring comes from large clefts in the moun- 

 tain, the bubbles are large ; but if from many small openings of 

 a porous rock, for example from Trass, the supplies are often not 

 larger than the gas pearls of Champaigne wine. From various 

 examples of remarkable regularity in the disengagement of car- 

 bonic acid gas, I select the following. Eight years ago I saw 

 in a mineral spring, besides many small gas bubbles which rose 

 uninterruptedly, also some larger ones which regularly, at an in- 

 terval of one and one-fifth seconds, followed one another with- 

 out interruption ; and seven years afterwards, when I again 



