S50 Prof. Bischof on the Temperature of 



•the opinion that they owe their heat to that of the interior of the 

 earth, it would still be impossible to account by that means for 

 the accidental variations which the temperatures of springs suf- 

 fer. And he maintains that his hypothesis is satisfactory in this 

 respect, the more particularly as such alterations generally take 

 place during earthquakes, and therefore prove themselves de- 

 pendent upon those great electrical phenomena (?). 



These objections are easily set aside. If alterations of the 

 temperature and chemical composition of springs generally hap- 

 pen during earthquakes, they may be caused by the opening or 

 closing of fissures, by which the waters come into contact with 

 other substances, or, by their coming from a greater depthj bring 

 with them the loose contents of the clefts in the rocks. If the 

 fissures open further, the atmospheric waters will sink deeper, 

 and become more heated ; if they close, the contrary will take 

 place. According to Dr Ambrozzi,* the warm waters of Tep- 

 litz flow more copiously since the earthquake which destroyed 

 Lisbon on the 1st November 1755, than before ; during the 

 earthquake they became muddy, flowed one hour and a half 

 of a dark yellow colour, and towards mid-day entirely disap- 

 peared during six or seven minutes, then suddenly gushed forth 

 again, and for half an hour continued to emit a thick yellowish- 

 red water, in such quantities that the baths were overflowed ; 

 whereas the medicinal springs of the village of Schonau, of Carls- 

 bad, and all others, with the exception of some in Morocco, re- 

 mained unaltered. 



An alteration of temperature and chemical composition has 

 often been observed in springs which rise in the vicinity of ac- 

 tive volcanos. Thus, according to Dolomieu,f the spring of 

 Macaluba, which in the year 1781 emitted atmospheric air and 

 carbonic acid gas, only yielded a kind of inflammable gas in the 

 year 1785. Other examples of alterations taking place in the 

 temperature of springs situated near active volcanoes will be 

 given afterwards. On the other hand, springs rising in the 

 neighbourhood of extinct volcanos shew a great uniformity 



• Physikalisch-Chemische Untersuchung der Warmen MineralqueUen zu 

 und bey Teplitz. Leipzig. 1797. 

 f Sur les Isles Ponces, p. 3G0. 



