REl'ORT ON MIN'iERAL AND THKRMAL. WATEES. 48 



bably derive their origin from a totally different cause, to that 

 which impregnates cold ones with this same principle. 



The latter in some instances undergo, within a very short 

 period, a material alteration in point of strength. 



Thus a sulphureous spring at Willoughby, in Warwickshire*, 

 yielded me in the autumn of 1828, 16'9 cubic inches of sul- 

 phuretted hydrogen to the gallon. 



In the April following, I could detect only 12'65 cubic inches, 

 and in the autumn of 1834 only 5 "2. 



Whilst on this svibject, I may mention, that Professor An- 

 glada of Montpellierf , has satisfied himself by a detailed exami- 

 nation of the svdphureous springs of the Pyrenees, that no one 

 of them contains sulphuretted hydrogen in a free state, but that 

 in every instance this principle is united to an alkaline base, 

 with which it constitutes an hydrosulphuret. 



Finding this to be the case so generally, he has proposed a 

 classification of sulphureous springs founded on this principle, 

 arranging them, according as they contain the above gas in a 

 free state, or combined with one, or two atoms of a base. 



By applying the same reagent (the arsenious acid,) which 

 M. Anglada had employed, I was led to conclude, that the 

 springs of Aix la Chapelle and Borset were similarly consti- 

 tuted, and indeed such would necessarily be the case, whei-e- 

 ever the soda in the water was not impregnated with carbonic 

 acid, nor could there well exist in it any free sulphuretted hydro- 

 gen, until the whole of the alkali was thus saturated. 



Hence in affirming that the gas of the Pyrenean springs 

 always occurs in this state of combination, M. Anglada has 

 (apparently unconsciously) confirmed the statement, which he 

 questions, as to the existence of caustic soda in the water. 



We have already considered whether under ordinary circuni- influence of 

 stances mineral springs are subject to vicissitudes, either as to <^3ith- 

 temperature, as to the quantity and quality of their fixed and ^pon^* 

 gaseous constituents, or as to the amount of water discharged, springs. 



It will be proper, however, before proceeding further, to 

 notice what has been observed, with respect to the influence 

 exei'ted upon them in any of the above respects by earthquakes, 

 which are stated in some cases to have aftected particular 

 springs in an extraordinary manner. 



During an earthquake in 1768 at Vienna, the spring of Baden 

 became more copious than before, and the evolution of sulphu- 

 retted hydrogen more abundant J. 



* Philosophical Magazine, Jan. 1835. f Me'moires pour servir, Sfc. 



X Kastner's Archiv, vol. v. 



