106 THERMAL WATERS OF ASIA MINOR. 



merely to show what this volcanic center has to do with the 

 thermal springs just described. 



REMARKS ON THE OCCURRENCE OF NITROGEN IN THERMAL WATERS. 



The only substance connected with these waters that I shall 

 allude to is the nitrogen contained in the gas accompanying 

 many of them, and in some instances constituting almost the 

 entire gaseous product, as in the case of the springs of Yalova. 

 This singular fact attracted my attention several years ago 

 while examining into the gaseous products of various springs, 

 and I then ascertained that the gas was found especially with 

 warm springs ; the nitrogen, when found accompanied with 

 oxygen, existed in proportions much greater than in the at- 

 mosphere, and in numerous instances it was almost pure. The 

 question naturally arises, whence comes this nitrogen? and as 

 we know of no other natural source of nitrogen than the at- 

 mosphere, it occurs to the mind that there is a source of the 

 gas in the thermal waters, which before they pass to the heated 

 substrata absorb a certain amount of air; the oxygen of the air 

 contained in the water combines with the rocks and minerals, 

 or is taken up by some deoxydizing agent in the waters, which 

 as they return to the surface naturally bring the nitrogen 

 of the air freed of all or most of its oxygen. 



This explanation, which appears so natural, does not, how- 

 ever, account for the fact, and I have been obliged to abandon 

 it. Did the nitrogen in these waters occur in such small quan- 

 tities as we might suppose to have been absorbed by water, 

 the explanation would hold good ; but the fact in the case of the 

 springs at Yalova and many other sources is that the gas, 

 which is nearly pure, bubbles up in great abundance. Again, 

 if the nitrogen evolved by springs be simply such as the water 

 absorbs before penetrating the surface of the earth, how does 

 it happen that this gas escapes from springs of ordinary tem- 

 perature? For it is reasonable to suppose that the water 

 having once taken into solution a gas, will not give it out 

 except by heat or the presence of a large amount of saline 

 matter, neither of which occur to explain the evolution of ni- 

 trogen gas from certain springs. 



Feeling thus satisfied that the nitrogen in the gaseous 

 products of springs is not owing to its absorption from the 



