REPORT ON MINERAI, AND THERMAL WATERS. G( 



which I have principally appealed, exhibited at Carlsbad, Mat- 

 lock, and Clifton. 



And it is only in the last of these instances, where, fortunately 

 for our argument, the evidence is of a more decisive character 

 than in the rest, that we are unable to strengthen it by other 

 collateral proofs, derived from the presence of intrusive rocks, 

 or the general appearance of the surrounding country. 



In the other examples cited, I might have been indisposed to 

 build upon this one fact, as a decisive proof of violent action 

 having taken place in the locality, had not the probability of 

 such events having occurred, obtained confirmation from other 

 circumstances that had been pointed out. 



Thus at Carlsbad, the existence of volcanic products both to 

 the east and west of the spot, as well as the propinquity of the 

 spring itself to a mountain range, which doubtless owes its ele- 

 vation to volcanic forces, together strengthen the inference 

 which the particular character of the locality would dispose us 

 to adopt. 



It appears then, that the geological position of thermal waters Theories of 

 in general leads to the conclusion, that they are connected with thermal 

 certain volcanic processes going on near the places in which ^P""s^* 

 they occur ; but it must be at the same time admitted, that in a 

 few special cases a high temperature is imparted to the springs Local 

 of a district, by causes of a more local and superficial character, causes. 



Thus Kastner* states, that in the Westerwald, between Ma- 

 rienburg and Stockhausen, the burning of brown coal under- 

 ground has caused so great a heat in the contiguous rocks, as to 

 give rise to several warm springs, which are characterized by 

 the presence of acetic and succinic acids, both probably derived 

 from the slow distillation of lignite. 



Setting aside, however, these comparatively rare and special General 

 cases, let us next briefly consider, how far the facts detailed in causes. 

 the preceding part of this Report, will assist us in explaining 

 the cause of that exalted temperature, which thermal springs 

 in common with other volcanic phaenomena exhibit. 



With respect to this question, a recent memoir by Professor 

 Bischof of Bonnf, may be quoted, as disposing successfully of 

 the hypotheses, in which certain chemical processes going on at 

 the present time near the surface, such, for example, as the de- 

 composition of pyrites, were appealed to, as capable of producing 

 the heat which these springs possess. He has also said enough 

 respecting another hypothesis, that of Anglada, who atti'ibutes 



* Arcliiv, vol. xvi. f Edinburgh New P/iilosop Ideal Joimiul.. April, 183G. 

 F 2 



