Hot and Thermal Springs. 36S 



are disengaged from them in greater or less abundance. * On 

 the other hand, there are others, rich in fixed substances, but 

 not containing more gaseous parts than the commonest well- 

 water. The temperature is not in proportion to the contents of 

 fixed substances, as has already been remarked, for cold mineral 

 springs frequently contain more than warm ones.-(* Gastein and 

 PfafFers are exampleft of this. But with regard to their ga- 

 seous contents, the temperature of springs is, in general, in the 

 inverse proportion, the reasons for which are already known. 



It is equally difficult to draw the line between warm and cold 

 springs. They form an uninterrupted series from the coldest 

 to the warmest. There certainly is no degree between 33^8, 

 the temperature of tlie coldest springs observed in Lapland by 

 Wahlenberg, and the boiling springs of Iceland, which does not 

 answer to some spring. The coldest springs of any place are 

 evidently those whose mean temperature is exactly equal to that 

 of the atmosphere; for no spring can be colder, unless its source 

 lie in neighbouring high mountains, from which it brings down 

 cold with it into the valleys. But as we can only become ac- 

 quainted with the coldest springs of any place, by comparing 

 their mean temperatures with that of the atmosphere, it is rather 

 difficult, from the temperature of springs, to deduce the mean 

 temperature of the earth or of the atmosphere at the place of 

 their origin. However, if we observe the temperature of several 

 springs in any place, during a whole year, the mean temperature 

 of the coldest of them will give a maximum which the mean tem- 

 perature of the place cannot surpass; and in many cases, that 

 maximum will be the real mean temperature of the place. That 

 the observations on the temperature of springs must be continued 

 for at least a year, in order to lead to any conclusions, is evi- 

 dent ; for in the hottest seasons, the spring of which the yearly 

 mean temperature is the lowest, will often be found to be warmer 

 than a neighbouring thermal spring whose temperature only ex- 

 ceeds the mean temperature of the place by a few degrees. From 

 the temperature of springs which are constant throughout the 

 year, or nearly so, certainly no conclusions can be drawn re- 

 specting the mean temperature of the place; for as there exist 



• See Bischof in the Journ. fur Prakt. Chemie, vol. i. p. 334. Note, 

 t Ibid. p. 340. and 341. 



