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PROFESSOR, FORBES ON THE TEMPERATURES 
The springs of the Eaux Bonnes, Bagneres de Bigorre, St. Sauveur, Bareges, Can 
diac, and Ussat appear in stratified rocks in close dependence upon granitic rocks, 
either in great masses or in small patches (as at Bagneres and Caudiac), which in- 
variably appear within a very short distance, and for the most part give proofs of al- 
teration or dislocation of the rocks. 
Lastly, what is extremely interesting, even where we find springs in the heart of a 
granitic chain, as near Olette in the valley of the Tet, where thermal waters issue in 
incredible numbers and run to the nearest mountain torrent, a patch of the stratified 
formations also appears. There is such an insulated deposit between Olette and 
Villefranche ; and whilst the springs first alluded to seem to be connected with its 
western extremity, we may probably refer to it the appearance of the waters of Vernet 
and Molitg* at the opposite one. 
In short, amongst all the nuclei of hot springs which I have visited in the Pyrenees, 
there is not a single exception to the connexion which I have mentioned. That this 
is the result of accident no one can for a moment suppose. But it seems very inex- 
plicable how we should have in many other countries a geological conformation al- 
most identical, without the appearance of hot springs. On the occurrence of fissures 
and metamorphic rocks in the case of many of the Pyrenean thermal sites, I shall 
speak when I come to enumerate them individually. 
I have only one more general remark at present to offer, and it seems important 
as to the theory of mineralization of these springs. A common opinion prevails that 
the quantity of the hydrosulphurets contained in these springs is in proportion to 
their temperature, and I have even heard the existence of cold sulphureous springs 
in the Pyrenees denied altogether. Yet not only are such to be found, but even within 
not many yards of others having a high temperature, and almost an identical mineral 
composition. Of this I have met with two examples in very different parts of the 
chain, one at the Eaux Bonnes (south of Pan), where a perfectly cold spring rises 
within two hundred yards of the principal hot spring of the place, has similar me- 
dicinal properties, and is even more strongly impregnated with sulphur, as I saw 
proved by direct experiment. The other example occurs at Las Escaldas, on the 
southern declivity of the Eastern Pyrenees, where a most efficacious cold sulphureous 
spring rises within about one hundred yards of a hot one. When to these facts we 
add others scarcely less curious, of springs of totally different mineral composition 
issuing from nearly the same spot, and with temperatures from 160° to 180° Fahr., 
as we see at Ax and at Thuez, we are forced to conclude that the source of minerali- 
zation must be independent to a great extent of that of high temperature, and that 
the arguments as to the origin of thermal springs founded upon their chemical com- 
position must be to a certain degree fallacious'f. 
* The waters of Molitg I have not visited. 
t A very singular circumstance was mentioned to me by M. Arago relative to the hot springs of Aix in 
Provence. A perforation having been made by an individual in their vicinity, though it yielded only cold water, 
