254 M Bischof on the Subterranean Course of Water, 



The rare opportunity has been presented me of measuring 

 the quantities of carbonic acid gas and water which some mineral 

 waters afford. I found the quantity of gas which flows out 

 from an acidulous spring, which may be considered as one of the 

 richest in carbonic acid, to be 4237 cubic feet in twenty- four 

 hours, and that of water afforded in the same time 1157 cubic feet. 

 As the water contains 1.65 times the volume of free and half- 

 united carbonic acid gas, the whole quantity of the absorbed and 

 the evolved gas amounts to 6146 cubic feet in twenty-four hours, 

 and, therefore, 5.3 times the volume of water. The temperature of 

 this mineral spring exceeds the mean temperature of the place 

 by about 4° R. ; and the spring must therefore come from a 

 depth, where there is an hydrostatic pressure of about 12 at- 

 mospheres.* If we assumed that the carbonic acid meets the 

 water at such a depth, then the latter could absorb more than 

 twelve times its volume of the former, therefore more than double 

 that it actually contains and gives off at the surface. Hence, 

 if the gas meets the water at half the depth of the course of this 

 spring, at a depth of 170 feet beneath the surface, the hydro- 

 static pressure at that depth would still be sufficient to take up 

 5.3 times the volume of gas. 



Another mineral water, from which there is also a very con- 

 siderable disengagement of gas, and in which, owing to the pe- 

 culiar construction of the well, the relative quantities of gas and 

 water can be measured with still greater accuracy, affords in twen- 

 ty-four hours 3063 cubic feet of gas, and 3645 cubic feet of water. 

 As the water contains 1.55 times the volume of free and half-unit- 

 ed carbonic acid gas, the whole amount of absorbed and evolved 



liowever, that the water at equal temperatures, even where there is so much 

 carbonic acid gas present as is required for its saturation, absorbs unequal 

 quantities of gas ; and experiments 5 and 6 shew, that, when less gas is pre- 

 sent than is sufficient for saturation, still all the gas will not be absorbed. 

 Hence when, under these circumstances, in equal low temperatures, unequal 

 quantities of gas will be absorbed, this will also be the case in high tempera- 

 tures. Thus it is not the differences of the quantity of gas absorbed at diffe- 

 rent temperatures %.'hich can be compared ; but it is the proportions of the 

 same with one another at different temperatures. 



• I shall not here explain that the increased temperatures of mineral wa- 

 ters, compared with that of common springs, depends chiefly on the depth of 

 their origin ; but I shall endeavour to prove this in another place. 



