the Waters of a Salt Spring in Huel Seton Mine. 35 



The analyses of the different rocks in the vicinity of the spring 

 have shown that the granite only could have furnished the 

 lithium, of which the waters have taken up a notable amount. 



A consideration of the various phenomena connected with the 

 occurrence of this and other apparently similar springs which 

 have at different times been discovered in the district, would 

 seem to lead to the inference that they all have some more or 

 less direct communication with the sea, and that they are either 

 the result of infiltration of sea- water through faults, or are true 

 and independent sources, which, before being tapped below the 

 sea-level, had found their way to the ocean through the faults or 

 channels before alluded to. 



It would be impossible to ascertain the precise conditions 

 under which springs of this description have been produced; 

 but the accompanying ideal sketch may perhaps assist in ren- 

 dering intelligible what would appear, in the present state of our 

 knowledge, a not improbable explanation of their origin. 



The plane AB C J) (fig. 2), being that of the cross-course, is 



Fig. 2. 



^5^^C 



seen to extend through both granite and clay-slate to the sea. 

 From the close contact of its surfaces, the presence of clay, and 

 from other causes, this fault is supposed not to be uniformly 

 permeable by water, which can only follow the circuitous pas- 

 sage, abed. In this way it penetrates to depths where reactions 

 take place, which, although not entirely in accordance with the 

 results of daily experience in our laboratories, can, after the in- 

 vestigations of M. Daubree, M. de Senarmont, and others, be 

 readily understood. 



By the action of sea- water on silicates of calcium, silicates of 

 sodium and chloride of calcium may be produced. The sulphate 

 of sodium of the sea -water will be decomposed by the chloride of 

 calcium, with the production of sulphate of calcium and chloride of 

 sodium. The decomposition of clayey matter by common salt 



1)2 



