32 Mr. J. A. Phillips on the Composition and Oriyin of 



Source whence the mineral waters of Huel Seton are probably 

 derived. — Before attempting to account for the presence of the 

 mineral constituents found in these waters, it will be neces- 

 sary to consider the bearing and importance of the following 

 facts : — 



{a) The average elevation of the surface of the mine is about 

 300 ft. above the sea ; and the 160-fathom level, being 960 feet 

 below the adit or drainage-tunnel and 1080 feet from the sur- 

 face, is consequently much beneath low-water mark. 



(b) The cross- course, shown in the accompanying geological 

 map, may, as has been already stated, be traced for a distance 

 of three miles to the coast, and apparently forms the channel 

 through which the saline waters effect an entrance into the 

 workings. 



(c) The water contains a very large proportion of chloride of 

 sodium. 



(d) Similar springs of hot saline water were met with, below 

 the level of the sea, in the neighbouring mines of North Roskear 

 and North Crofty, both situated on the same cross-course. These 

 waters have not been analyzed. 



(e) A hot spring yielding waters possessing the same general 

 characteristics as those from Huel Seton, formerly issued at the 

 Huel Clifford Mines in the 230-fathom level, or at a depth of 

 1320 feet below the sea. It will be seen, by referring to the 

 Map, that in this case a well-defined cross-course can be conti- 

 nuously traced in a north-westerly direction from the immediate 

 vicinity of the spring to the sea at Tobban Cove*. 



* These mines are now abandoned and consequently flooded. The 

 waters issued at a temperature of 125° F., and at the rate of 150 gallons 

 per minute. The late Dr. W. A. Miller, who analyzed them in 1864, ob- 

 tained the following results : — 



Sp. gr. = 1*007. The saline constituents were found by evaporation to 

 amount to 646" 1 grains per imperial gallon, consisting of: — 



Chloride of lithium 2605 



Chloride of potassium with a little chloride ) 14.04 



of caesium J 



Chloride of sodium 363*61 



Chloride of magnesium 8'86 



Chloride of calcium 216*17 



Sulphate of calcium 12*27 



Silica 3*65 



Oxides of iron, alumina, and manganese, minute quantity 



645*45 



(" Chemical Examination of a Hot Spring in Huel Clifford, Cornwall, 

 by Professor W. A. Miller, M.D. &c," Report of the Thirty-fourth Meet- 

 ing of the British Association &c, held at Bath, September 1864.) 



