28 SIXTH REPORT 1836. 



becomes intelligible, when we reflect, that although dry boracic 

 acid continues fixed at high temperatures, yet when steam is 

 passed over it at a red heat, a portion of the acid is always sub- 

 limed, as I have myself ascertained by experiment. 



Whether the same explanation will apply to the case of the 

 lakes of Thibet, whence so large a quantity of borate of soda is 

 obtained, future travellers must determine. 



Nitric Acid. Nitric acid, united probably with potass (this alkali being 

 found along with it), sometimes occurs in the springs of large 

 towns, as observed by Pagenstecher* in those of Berne, and by 

 Berzelius in those of Stockholmf. 



There is also a tract in Hungary, included betwixt the Car- 

 pathians and the river Dran, throughout which all the springs 

 are said to be impregnated with this ingredient|. 



The spontaneous production of nitre, wherever organic matter 

 in a state of decomposition remains in contact with calcareous 

 rocks, or with earth containing carbonate of lime, may suffi- 

 ciently account for its existence in such springs as these, which 

 probably owe their origin rather to superficial than to deep- 

 seated causes. 



It remains, however, to be inquired, whether the same ex- 

 planation can be extended to the waters of St. Alban, Dep. de 

 Loire §, and of Miinchhof|| in Germany, in both of which nitre 

 is said to be present, and that not, as in the former cases, in 

 variable, but in fixed proportions. 

 Ammonia Can we attribute to the same decomposition of organic mat- 

 in Springs, jpj, jj-jp presence of ammonia in certain mineral waters ? 



Scherer^ mentions a sidphureous spring in Courland, which 

 contains it in union with the muriatic acid ; and Osann** one 

 at Raab in Hungary ; whilst Berzelius ft notices its occurrence 

 in the mineral waters of Porla, united with a peculiar acid, the 

 creiiic, which will be noticed presently. 



Longchamp also states, that there are traces of it in some of 

 the thermal springs of tlie Pyrenees ; but he does not state in 

 M hat state of combination it occurs. 



Professor Fischer J:]: of Breslau has detected it in conibination 

 with cai'bonic acid in the thermal water of Warmbrunn, in 



* Uehersicht dcr Bestandih. der Brunnen der Studt Berne. 



■\- Osann, vol. i. p. 92. + Ibid. 



§ Patissier Manuel des Eau.c Minerules, p. 280. 



Ij .Schweigger, Journal, vol. xlv. 



il Page 180. ** Page 85. 



+ 1 Pldl. Magazine, vol. vi. p. iSQ. 



II Groel'e, Jahrbuchci- fur Deulchlands Heilquelkn, 1836. 



