36 On the Chemical Constitution and 



may infer them to have a connexion with the springs. That 

 this is the case in several other parts of the world, he shews by 

 several examples. 



If we now bring under our view what the above has taught 

 us regarding hot springs, we come to the three following general 

 conclusions: — 1. We find hot springs and exhalations of hot 

 gases and vapours near all active volcanoes, whence we conclude 

 them to be intimately connected with volcanism. We also see, 

 that permanent hot springs appear when the proper eruptions, 

 which occur only from time to time, have ceased *. 2. We also 

 find warm springs near extinguished volcanoes, as well as those 

 mountains whose igneous origin is no longer disputed : But it 

 appears that the temperature of hot springs is higher near active 

 than extinguished volcanoes. 3. We lastly find warm springs 

 in primitive mountain chains, which present on their surface no 

 volcanic products; but which some geologists regard as raised 

 by the general volcanism of the earth, at the period of its great- 

 est activity -f". 



From what we have said before of hot springs, coming under 

 heads 1. and 2., we may so lay down the principle, because hot 

 springs, which we regard as the products of volcanic action, ap- 

 pear in the neighbourhood of active and extinguished volcanoes ; 

 we also infer, from what has been previously said of such 

 springs in primitive mountains, which shew no volcanic produc- 

 tions, the existence of volcanic activity at a greater depth. 



I have already hinted at the fact, that the temperature of the 

 earth increases with the depth. So far we are obliged to admit 

 volcanic action at a great depth J, to which the atmospheric wa- 



• Vesuvius and Etna liave a numbei- of hot .springs. The now dormant 

 volcano on Ischia has hot spi-ings. In the volcanic district of the Lake of 

 A^nano, the Piscarelli are 93°. Iceland is quite filled with hot springs, of 

 which the Geyser, of 80°, is best known. The volcanic West India Islands 

 shew the same phenomenon : likewise the volcanoes in Java, in Japan, where 

 the sjmngs of Ungino have a temperature of 100°; in America, &C. Kefer- 

 stein, ut antea, p. 49. Also "Von HofF, utantea, vol. ii. p. ^79, 481, 485, 518, 

 548. 



-l" Von Hoff, ut antea, ]). 553. 



X Compare Von Hoflfj ul antea, p. 366, 367, and 549. 



