and on the Absorption of Gases by Water. 255 



gas in twenty-four hours is 871.3 cubic feet, therefore 2.4 times 

 the volume of the water. The temperature of this mineral well 

 is greater than the mean of the common springs at that place by 

 about 4° R., and the spring must therefore come from a depth 

 where there is a hydrostatic pressure of about 12 atmospheres. 

 If the carbonic acid meets the water at this depth, tlien twelve 

 times the volume could be absorbed, that is, more than four times 

 the quantity contained in it, and given out at the surface, &ec. 



I am not aware that any similar measurements, which natu- 

 rally presuppose an air-tight construction of the well, have been 

 made. TrommsdorfF* has indeed measured the quantity of 

 carbonic acid gas which is evolved from the gas spring at 

 Kaiser-Franzensbad, and also that of the water afforded by the 

 four mineral springs, and of the free and half-united carbonic 

 acid ; but he could not measure the free carbonic acid gas which 

 flows from the springs. The quantity of the gas from the gas 

 spring, viz. 5760 Vienna cubic feet in twenty-four hours, appears 

 very great ; if we compare this with the quantity of water which 

 the four mineral springs afford, 259 cubic feet in twenty-four 

 hours, it may well be assumed that this quantity of water can, 

 at a depth beneath, retain absorbed not only the gas which it 

 contains and gives off, but also the gas of the gaseous spring, 

 and that the latter nearer to the surface, under diminished pres- 

 sure of water, is separated from the water, and through a side 

 canal appears as a gas spring at the surface. 



In this manner most of the carbonic acid gas springs, that is, 

 exhalations of gas without the flowing of water, have been pro- 

 duced. The volcanic Eifel, and the environs of the Laacher- 

 See, present many sucii gaseous springs or exhalations ; one of 

 them, that called the Brudcldreis, near Birresborn, was described 

 ten years ago by Professor Ndggerath and myself. -f- These ex- 

 halations sometimes issue from alluvial soil or loose earth, and 

 we recognise their presence only by the stunted vegetation and 

 the suffocated little animals on such spots. There is no hissing 

 noise, and the smell of the carbonic acid gas can be perceived 

 only by placing the face close to the ground. In other places 

 these exhalations come to the surface with a hissing ikmsc from 



• Kaiser-franzensbad bei Eger von Osann und Trommsdorf, 2d edit. p. 134, 

 f Schweigger'3 Journ. fur Chemie und Physik, vol. xliii. p. 28, &c. 



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