TIN STOCKWOEKS IN COENWALL. 659 



be the roots of mineral springs. We yet want to know more about 

 the solubility of minerals under great pressure and at a very high 

 temperature. Many are probably soluble under such conditions 

 which are not so under the ordinary conditions at the surface ; and 

 if this be the case we need have no great difficulty in understand- 

 ing their deposition and also the alterations in the rocks. 



Prof. Ramsay, referring to Mr. Sollas's inquiry as to the common 

 theory of mineral veins, said that long since it used to be taught 

 that the minerals were brought up from below by the agency of 

 vapours ; afterwards that the minerals in the lodes and in the altered 

 rocks about them were accumulated by the aggregation of minerals 

 diffused in minute quantities throughout the rocks on either side. 

 He referred to a deposition of copper from aqueous solution in a 

 peat-moss in Wales, the solution having proceeded from a distant 

 hill. The peat was worked, and much copper obtained from it; 

 and in consequence of this the hill was bored in many directions in 

 search of a lode of copper-ore, but nothing was met with except a 

 few thin strings not worth a farthing. It had been long since shown 

 that in Derbyshire fissures in anticlinals were unproductive, but 

 those in synclinals productive of lead-ore ; and this was explained by 

 the lead being dissolved by the water falling on the surface, which, 

 travelling along the planes of stratification, conveyed it from the 

 convexities and towards the hollow folds of the beds. 



Mr. De E-ance stated that the mode of occurrence of lodes in 

 Alston Moor was confirmatory of what Prof. Eamsay had just said. 



