REPORT ON MINERAL AND THERMAL WATERS. 19 



But looking to their origin, or the materials from which they 

 are derived, they must be grouped with salt springs of the com- 

 mon kind, as I have shown in the memoir already quoted. 



I may appeal indeed to the authority of Mr. Murchison *^ 

 when I state, that these waters, like the genuine brine springs 

 of Cheshire and Worcestershire, rise out of the new red sand- 

 stone formation. Hence it is probable, that their original con- 

 stitution is analogous, but that during the passage of the 

 water upwards through cracks and fissures in the lias clays 

 overlying, the iron pyrites, which is so abundant in that stratum, 

 supplies it by its gradual decomposition with the sulphuric acid 

 found amongst its ingredients. 



That sulphuretted hydrogen is generated in the vicinity of 

 these springs, we are assured, not only from the minute quan- 

 tity of this gas observed in one or two of the Cheltenham and 

 Leamington waters, but also from the strong impregnation of the 

 spring of Willoughby in Warwickshire, as noticed by myself, 

 and of that of Haslar in Worcestershire, reported by Dr. Hast- 

 ings-}-. 



Now, if we grant the sulphuric acid to be derived from this 

 source, the other differences between these saline aperients, and 

 brine springs properly so called, will admit of an easy solution. 



The sulphuric acid, acting upon the several muriates, would 

 form with their bases those earthy and alkaline sulphates on 

 which their medicinal qualities chiefly depend ; whilst the free 

 muriatic acid disengaged, attacking the calcareous rocks, would 

 give rise to the production of the increased quantity of muriate 

 of lime present in them. 



With respect, therefore, to the origin of the above ingredients 

 modern discovery has added little to the general principle laid 

 down by Pliny, " Tales sunt aquas, qualis terra per quam fluunt." 

 For it seems needless to attempt tracing them further than the 

 rocks from which the springs themselves issue. 



But there are other substances of occasional occurrence that 

 cannot be referred to this source, so immediately, or without a 

 more particular inquiry into the circumstances of their appear- 

 ance. 



Of this description are two acids discovered recently in mi- Phosphoric 

 neral waters, namely, the phosphoric, and the fluoric, an addition ^^j.f(j^'"°"*^ 

 to our knowledge for which we are indebted to the analytical 

 skill of Berzelius. Subsequently, the former substance has 



• Proceedings of the Geological Society, vol. i. p. 390. 

 + Salt Springs of Worcestershire, p. 9- 

 c 2 



