ORIGIN OF HOT SPRINGS. 197 



(147), Toeplitz (117), Carlsbad (164), Baden-Baden (153), Gastein 

 (117), Aix-les-Bains (116), Leukerbad (124), with many more in 

 Central France, the Pyrenees, Hungary, Italy, and other countries. 

 For the most part these springs are at moderate elevations above the 

 sea, Wiesbaden being 323 feet and Aix-la-Chapelle about 500 feet; 

 but at Gastein the spring rises at 3100 feet, and at Leukerbad at 4400 

 feet ; while in South America hot springs occur in Chile at a height of 

 upwards of 12,000 feet. Bischoff l has ingeniously calculated that by 

 supposing water to collect on the Balm Horn above the Baths of Leuk at 

 an elevation of 10,292 feet, where it is assumed to be liquid, it would, 

 by flowing down the clefts in the interior of the mountain, be raised 

 to a temperature of 125 F. on reaching Leukerbad, supposing the tem- 

 perature to rise 2^ F. for every 145 feet descended. Therefore, the 

 temperature of hot springs is never above that which may be derived 

 from the earth ; but their existence in regions of existing and former 

 igneous action may well be compared with the positions of geysers. 

 Some, like the hot springs of Bertrich, slowly decline in temperature ; 

 and earthquake disturbance has raised the temperature of others. 

 The substances dissolved in hot springs vary with the nature of the 

 rocks through which the water flows, and with the temperature. 



The evolution of gas is often considerable. It is commonly 

 carbonic acid, as in nearly all the springs of volcanic districts, and 

 those which rise through faults, or else it is sulphuretted hydrogen. 

 Often there is a large evolution of nitrogen, as in the waters of Bath, 

 Buxton, and many continental springs. Frequently the waters are 

 so charged with carbonic acid as to form natural soda waters, and 

 sometimes carbonic acid escapes from fissures without any indication 

 of springs, as in the Mofettes, near Laach, and Gerolstein, and many 

 localities in Italy. The salts dissolved in the waters of springs are 

 usually carbonates and sulphates, but chlorides, phosphates, and 

 fluorides are also found. The waters of Carlsbad (which contain 

 about 463 grains of solid matter to the gallon) yield as the 

 principal substance sulphate of potash, but there are small quantities 

 of arsenic, iodine, bromium, antimony, gold, copper, chromium, 

 manganese, zinc, cobalt, nickel, titanium, barytes, strontian, lithium, 

 fluorine, selenium, phosphoric acid, and boracic acid, besides several 

 organic acids and traces of resinous substances. 



The hot springs of Cornwall at Wheal-Ciifford, near Kedruth, 

 yield a large quantity of lithium, and are rich in chlorides of sodium 

 and calcium. Professor Daubeny 3 has given a statement of the salts 

 found in the principal thermal springs in a tabular view, from which 

 it will be seen how variable are the salts contained, and how different 

 are the geological formations through which the waters rise. But, 

 in every instance, the conclusion is forced upon us that these salts 

 are to a large extent such as would be yielded by the decomposition 



1 Bischoff, " Physical, Chemical, and Geological Researches on the Internal 

 Heat of the Globe.'' 1841. 



2 Lyell Address, Brit. Association, Bath, 1864, p. 65. 



3 ' "Volcanoes," id ed. 



