THE FORMATION OF SALINE MINERAL WATERS. 827 



waters, with the immense variety of labors of which they have been 

 the object, the fundamental questions relating to them still remain 

 enveloped in profound darkness. An examination of the most recent 

 and most authoritative publications suffices to show us that, with re- 

 gard to the most capital point, the origin and mode of formation of 

 these waters, we, at the end of fifteen centuries, are not much further 

 advanced than were the Romans. Modern science, it is true, has put 

 the ancient nymph to flight, and driven from his sanctuary the little 

 beneficent god that presided at each fountain ; but it has not yet suc- 

 ceeded in raising the statue of the truth upon the vacant altar. 



Mineral waters take up the substances which give them their pecul- 

 iar composition, and acquire all their medical value, at greater or less 

 distances within the globe. It is, then, for geology, the science which 

 deals with the formation of the globe, to seek the solution of the ques- 

 tions of their origin. 



The number of mineral springs is immense, and the variations 

 among them seem infinite ; but there exist among them certain groups 

 which distinguish and separate themselves at the first glance. Among 

 these we place in the first rank the saline waters, or those of which 

 the sea is the type. This is the division which I propose to consider, 

 and of which I shall endeavor to set forth the origin and method of 

 formation. 



It is a fact, which I may state as uncontested at the present time, 

 that all spring-waters, whether mineralized or not, are of exterior 

 origin that is, are waters of infiltration derived from the atmosphere. 

 When these waters return to the light without having met, in the strata 

 they have traversed, either soluble minerals or gases other than those 

 of the atmosphere, they constitute ordinary waters. If, on the con- 

 trary, they have met soluble substances or gases different from those 

 of the atmosphere, they will return more or less charged with those 

 substances, and will then be mineral waters. In studying them we 

 need not, therefore, inquire about the origin of the water itself, for it 

 comes from the atmosphere, but only about that of the saline sub- 

 stances which it has encountered in its course. 



It has been known from the most remote antiquity that consider- 

 able masses of saline substances, generally composed of gypsum, more 

 rarely of rock-salt, exist at numerous points of our globe. The two 

 salts we have named are the ones that have hitherto attracted the 

 attention of commercial and scientific men ; but the saline beds are in 

 reality of a more complex composition than is superficially indicated 

 by the predominance of those compounds. 



The hypotheses which have been proposed to account for the origin 

 of these salts, though many, may be grouped around three principal 

 heads : 1. Free sulphuric acid, coming up from the depths of the 

 globe, has acted u^on carbonate of lime already formed and produced 

 gypsum. 2. Hydro-sulphuric acid, coming in like manner from the 



