844 Prof., Bischof on the Temperature of 



deed, warmer the more salt they contahi (vvhich is considered 

 a general rule by salt-workers), and as it may be considered 

 quite certain that they derive their saltness from deposits of rock- 

 salt, a contradiction here presents itself, and we must conse- 

 quently conclude, at least for salt-water springs, that they are 

 not indebted to chemical processes of the first kind for their 

 superior temperature. 



The greatest evolution of heat would take place, if the ele- 

 ments of the salts, contained in the mineral springs, entered into 

 combination at the moment of the creation of those springs. In 

 order to have an idea of the degree of heat which would be pro- 

 duced in this case, I made the following experiments : — 



The Heilbronn, a mineral spring in a small valley of the 

 Brohl, four miles distant from the lake of Laach, is, next to 

 Bilin in Bohemia, the richest in carbonate of soda known to 

 me. It contains 0,0053 of fixed substances. Supposing that 

 this spring were formed from anhydrous carbonate of soda, by 

 the addition of concentrated sulphuric acid, muriatic acid, and 

 water, then, according to my analysis, 77,4 parts anhydrous 

 carbonate of soda, 5 parts concentrated sulphuric acid, 92 of 

 smoking muriatic acid, and 22,G87 parts of water would be 

 required to compose a water, containing the same proportions of 

 carbonate and sulphate of soda, and of chloride of sodium, as 

 that spring. In accordance with this, therefore, I put 77,4 

 grains of calcined carbonate of soda to 22,687 grains of water. 

 The temperature of the water was, — 



Before the experimient, 42''.8 



After, 43°.7 



Increase of temperature, 0°.9 



To this solution of soda I added a mixture of 5 grains con- 

 centrated'sulphuric acid, and 92 grains smoking muriatic acid. 

 The temperature of the two liquids was, — 



Before their mixture, . , T . . SO'.OO 

 After, 50».45 



Increcse of temperature, 0*.45 



Now, although such a chemical pr.xess as this, which is very 



improbable to take place in the interior of the earth, is the most 



favourable for the production of heat ; still, it only caused a^^ 



