68 On Mineral Waters, 



Sir Humphrey Davy*, and my own experiments f ; and, on fol- 

 lowing up the experiments of Professor Kastner, at the mineral 

 springs on the Rhine and in Bohemia, I ascertained that they 

 evinced no signs of electrical action whatever, and that their 

 mode of affecting the electro-magnetical multiplicator differed 

 in no particular from that of an artificial mineral water, contain- 

 ing the same ingredients. The source of the error into which 

 Professor Kastner had fallen, I have pointed out in an earlier 

 number of the above-mentioned philosophical journal \ . Thus 

 experience subverts the first ground of objection. 



Another is, that the warmth of thermal springs is dif- 

 ferent from that obtained by artificial means. They have been 

 asserted to produce a different sensation on the frame, and to 

 demand a longer period for the reduction of their temperature 

 than common water heated to the same degree. 



If the sensation produced by a naturally thermal bath dif- 

 fers from that of common water, heated to the same temperature, 

 the reaction caused on the skin by the ingredients of the former 

 must be taken into account. With respect to the greater length 

 of time which the mineral water is supposed to require in cool- 

 ing, the circumstance has been disregarded, that the bathing 

 reservoirs, being mostly constructed of such materials as 

 belong to the worst conductors of heat, retain a temperature 

 little inferior to that of the bath itself Nor is it possible, in a 

 close chamber, where no current of air is permitted, and whose 

 atmosphere, consequently, soon becomes saturated with vapour, 

 that the temperatue of the water can be sensibly diminished by 

 evaporation. 



Authenticated proofs, however, afford us a still better means 

 of refuting such gratuitous assumptions. With this view, M. 

 Longchamp submitted the waters of Bourbonne,§ which prior 

 examinations || had endowed with a different capacity for caloric 

 than a corresponding factitious mixture, to a careful and minute 

 course of experiments ; and the results proved that the water 



* Fide Philosophical Transactions for 1826, III. 

 t Vide PoggendoflF's Annalen der Physik, 1825, Nos. 7 and 8. 

 X Fide Poggendoff' s Annalen der Physik, 1825, No, 5. 

 § Fde Annales de Chimie et de Physique, torn. xxiv. p. 247. 

 II Recueil des Memoires de Medecine et de Pharmacie Militaires, xii. p. 21.— 

 Paris, 1822. ^ 



