ORIGIN OF SULPHUR SPRINGS. 155 



iron pyrites which exist in any one portion of these rocks, would certainly lead to the conclu- 

 sion that the source of these impregnations is much deeper than that which is here assigned 

 to them. 



But another strong objection to this theory of the origin of sulphureous springs is, that they 

 very rarely contain sulphate of iron among their saline constituents. Now it is well known 

 that the very agencies which would cause the evolution of sulphuretted hydrogen from iron 

 pyrites, would also give rise to the formation of sulphate of iron. This being a soluble salt, 

 we cannot understand why, if these waters are due to the decomposition of iron pyrites, they 

 should not in every case contain the very substance which is at least one of the results of this 

 decomposition. 



Such are the objections to this view of the origin of these springs, even in those cases most 

 favourable to its adoption ; viz. where the springs emerge from strata which usually contain 

 iron pyrites. But they are greatly increased in force, when the theory is proposed to be 

 applied to those districts which are not thus characterized. We then have the additional 

 difficulties presented, viz. the emergence of these springs from the oldest as well as the more 

 recent rocks, as is .exhibited in the State of New-York, and the vast amount of sulphuretted 

 hydrogen which they evolve ; an amount, which I think few would presume to refer to such 

 an agency as that of the decomposition of iron pyrites, which seldom exists in any abundance 

 in the older class of rocks. 



We cannot, therefore, I think, without great violence, refer these springs to a local origin, 

 which is insufficient to explain their widely extended occurrence, while a more general ex- 

 planation virill be equally applicable to all the facts which have been observed. 



There are two general theories in regard to the origin of mineral springs. In both of them 

 a general focus of action is recognized, which not only gives rise to what are usually con- 

 sidered as volcanic phenomena, but to mineral springs of whatever character, whether thermal 

 or not. In one case, however, these phenomena are supposed to result from the mechanical 

 action of the solidified crust of the earth upon a fluid nucleus, the state of fluidity being the 

 result and the evidence of intense heat. In the other theory, they are ascribed to chemical 

 processes carried on within the earth ; these processes, however, being the same in their 

 character as those which give rise to volcanic eruptions. In other words, they are the direct 

 products of the great volcanic focus existing in the interior of the globe ; and that volcanic 

 action, of which they form one of the manifestations, is to be ascribed to a chemical agency.* 



In the case of sulphureous springs, the substances necessary to their composition are water, 

 sulphur, the alkaUne and earthy bases, together with minute portions of carbonic acid and 

 oxide of iron ; the two last of which, however, may be independent of the general agency. 

 All these bodies are known to be the products of active volcanoes — a circumstance of great 

 importance in the discussion of this subject. This theory also receives confirmation from all 

 the other facts which have been stated in regard to these springs, viz : 



* On these general views, I would refer to a valuable paper, "On the Probable Origin of Mineral Springs," by C. E. Stifll, 

 formerly Mining Engineer to the Duke of Nassau. Edinburgh Nrw Philosophical Journal, XII. 290. — And also to an article " On 

 the Mineral Springs of Iceland," by C. Krug Von Nidda ; republished in the same work, Vol. XXII. 90. 



