and their Connexion with Volcanos. 65 



But there is a third description of air, the existence of which 

 seems calculated to throw further light upon the nature of the 

 process, being more generally met with than either of the two 

 former, and being common alike to the springs belonging to 

 each of the three kinds of situation to which they may for the 

 most part be referred. The gas alluded to is nitrogen, which, 

 as already stated, was found by Longchamp and others in 

 every hot spring that had come under their examination within 

 the compass of the Pyrenees. In those of volcanic districts it 

 seems to be less common, nevertheless it has been found by a 

 recent chemist, emitted in large quantities from a spring at 

 Castellamare, in the Bay of Naples ; and it has been detected 

 by myself, mixed with a predominant portion of carbonic acid, 

 in the hot springs of Mont Dor and Bourboule in Auvergne, 

 and in those of Chaudesaigues in Cantal, whilst at Vichy Long- 

 champ has ascertained its existence under the same circum- 

 stances. 



The gas evolved from the thermal waters of the Alps 

 seems to be the same in a state of nearly perfect purity ; the 

 carbonic acid, which probably accompanied it, being in these 

 cases absorbed by the water through which it had to pass. 

 Thus, on the Savoy side of that chain, I discovered it issuing in 

 large quantities from the spring of St Gervais ; and, on the Ita- 

 lian side, from those of Sainte Marguerite at Cormayeur, of 

 St Didier in the same valley, and of Bonneval in the Taran- 

 toise, half-way between the Bourg St Maurice and the Col de 

 Bonhomme. In only one of these springs, that of Bonneval, did 

 any carbonic acid appear to be present ; and in this case it 

 amounted to about 12 per cent, of the whole quantity emitted. 



Dr Ure also mentions his having detected azote issuing in a 

 state of purity from the baths of Louesche in Switzerland, 

 Neither is this gas absent even from hot springs, which, like 

 those met with in our own country, occur at a distance from 

 great systems of elevation, such as those of which the Alps and 

 Pyrenees afford us examples. It has long ago been detected in 

 the Bath and Buxton springs ; and I have myself, more lately, 

 discovered it in two other tepid waters already noticed as belong- 

 ing to the same country, and probably influenced by the same 

 causes, as that of Buxton. The springs I allude to are those of 



OCTOBER DKCEMBER 1831. E 



