Temperature of Springs. SI 



ter must sink to acquire its heat; yet nothing prevents its being 

 warmed by the high temperature at that depth, independent of 

 volcanic fires ; and, in such a heated state, again appearing at the 

 surface, if it must still rise so high ; for, if the channels through 

 which it flows become once heated, their walls would conduct 

 little heat outwards *. Berzelius seems inclined to attribute this 

 origin to the tepid, non-alkahne, but partly saline, and slightly 

 sulphureous waters, which spring from a granitic soil, in which 

 we find no volcanic remains -|-. 



I rest satisfied here with merely having pointed out this pos- 

 sible cause of the warmth of springs ; for it would be difficult, 

 in a field where we have merely grounds of probability, to pro- 

 nounce any thing decisive. 



I now resume the thread of my investigation. 



Keferstein and Von HofF have endeavoured to shew that hot 

 springs constantly accompany volcanic ridges, but without pay- 

 ing any attention, in their observations, to their chemical consti- 

 tution. Berzelius has, from the occurrence of mineral waters 

 which contain soda saturated with carbonic acid, in the volca- 

 nic districts ol the Bohemian Mittelgebirge, in Auvergne and 

 the Vivarais, inferred their connexion with volcanic agency. 

 I have also observed this connexion in the mineral waters ana- 

 lyzed by me, at Geilnau, Fachingen, and Setters ; and which I 

 will now endeavour to point out in the great basaltic or vol- 

 canic mountain chain, which begins in the Eifel, and extends 

 to the Riesengebirge. I divide this basaltic chain into seven 

 separate groups, and describe those springs containing carbonic 

 acid, saturated with soda, with their relation to the geognostical 



• A remark naturally deduced also regarding springs warmed by volcanic 

 activity. 



-f- If we look at the numerous existing observations on the temperature 

 in the interior of the earth (see Annales de Chimie and de Physique, v. xiii. 

 p. 183), we will observe a considerable increase of temperature at compara- 

 tively trifling depths. Thus Gensanne found in the mines of Giromagni, 

 at Befort, in a difference of depth of 332 metres, a difference of temperature 

 of 10*.2 C. viz. in a depth of 433 metres + 22°.7 C. In the mines of Corn- 

 wall, the temperature, at a depth of 348 metres, was -|- 26* ; while, at the sur- 

 face, it was -|- 15^ Von Humboldt found in a mine of New Spain, in America, 

 at a depth of 502 metres, -j- 330.8 C, while the mean annual temperature is 

 there 16* C. We see from this, that water, which has sunk to no great depth, 

 may be heated from 22*.7 C. to 26" or even 33*.8 C, 



