24 Mr R. W. Fox on the High Temperature 



of the place, and two ** elvan courses'* traverse the mine in 

 nearly the same E. and W. direction as the lode. 



I have found that J of a pint of the water from the warmer 

 spring contained 15 grains of saline matter, consisting of 

 muriate of lime and common salt — in about equal propor- 

 tions, — with a trace of sulphuric acid, probably combined with 

 lime. In the same quantity of the cooler water, only lOi 

 grains of muriate of lime and common salt were found, — the 

 latter in less proportion than the former, — and in this water 

 also there was a slight trace of sulphuric acid. In both in- 

 stances the water was clear, saline to the taste, and without 

 any metallic salt. 



It may, I think, be inferred from the saline contents of 

 these springs, that they have a common origin or source ; 

 whilst their high temperatures indicate their having come 

 from a considerable depth, and the quantity of water they 

 discharge, that the lode, or rocks beneath, must be very per- 

 vious to it. In these instances, at least, there are no grounds 

 for supposing that any chemical decomposition of the sulphur 

 ores in the lode has caused the high temperature of the 

 water, or contributed to it in any degree, seeing that it con- 

 tains no metallic, and scarcely any sulphate salt. 



The difference in the heat of the two springs may, perhaps, 

 in part, be attributed to the tendency of the warmer currents 

 to rise towards the upper wall of the lode ; and, still more, 

 to that of water at a much lower temperature passing from 

 superior strata down upon the inclined surface of the lower 

 wall, where, mixing with the water rising from below, the 

 temperature becomes modified, as well as the proportion of 

 the saline contents. 



It cannot be doubted that ascending and descending cur- 

 rents of water, more or less copious, and at different degrees 

 of temperature, abound in the veins and fissures of the earth, 

 and often at the junctions of different rocksf, and that they 

 must have a great influence in modifying the subterranean 

 temperature, and in different degi^ees in different places. 



Common salt is of rare occurrence in our mines ; its pre- 

 sence in the water in question cannot well be attributed to 

 the flowing of sea-water into the excavation, in consequence 



