56 



PROP. EDWARD HULL, LL.D., F.K.S., T.G.S., ON 



liquor which remains are to be fonnd the more soluble bi'oraides 

 and chlorides of potassium, &c. The result is that the salt ob- 

 tained in this manner direct from sea water corresponds almost 

 exactly in composition with the rock-sal fc of Cheshire, as the fol- 

 lowing table will show : — 



" Thus, while sea water contains about 78 parts in 100 of chloride 

 of sodium or common salt, the salt procured from it by evapor- 

 ation consists of 98-80 parts in 100, which corresponds within a 

 fraction with the proportion (98-32) existing in rock-salt." 



The third is from Mr. J. Postlethwaite, F.G.S. : — 

 "I have read Professor Hull's paper on ' How the Waters of 

 the Ocean became salt,' with mu^ch interest, chiefly because my 

 attention had been directed to the subject whilst endeavouring to 

 investigate the source of certain mineral springs, near Keswick, 

 for the purpose of laying the results of such investigation before 

 the members of the Cumberland and Westmorland Association for 

 the Advancement of Literature and Science, at their Annual 

 Meeting in 1886. (See Trans. C. and W. Assoc, vol. xi, p. 142.) 



" The existence of those springs is a further confirmation of 

 Professor Hull's statement that ' from direct physical evidence 

 the waters of the early Silurian oceans were salt ' (sec. 7). The 

 salt spring at Brandley Mine, on the margin of Derwentwater, 

 issues from the Skiddaw Slate, in the lower part of the Oi'dovician 

 (Lower Silurian) System ; it contains a lai'ge amount of mineral 

 matter in solution, namely, 203-78 grains per imperial pint, con- 

 sisting of : — 



Chloride of calcium ... ... 87-67 grains per pint. 



,, ,, magnesium ... ... 1-53 ,, ,, 



,, ,, sodium ... ... 110-23 ,, ,, 



Sulphate of magnesia ... ... 4-35 ,, „ 



Total 203-78 



