II. 



ON SOME POINTS IN CHEMICAL 

 GEOLOGT. 



(1859.) 



A paper with the above title was sent to the Geological Society of London in 

 August, 1858, and read before that body, January, 1859. An abstract of it appeared 

 in the L. E. & D. Philosophical Magazine for February, audit was published in full in 

 the Quarterly Journal of the Geological Society for November, from which it was re- 

 printed, with the addition of a few notes, in the Canadian Naturalist for December, 

 1859. Such portions of this paper as were but a repetition of the preceding one are 

 here omitted ; what follows may be regarded as a supplement to that. 



WHEN we examine the waters charged with saline matters 

 which impregnate the great mass of calcareous strata constitut- 

 ing in Canada the base of the palaeozoic series, we find that 

 only about one half of the chlorine is combined with sodium ; 

 the remainder exists as chlorides of calcium and magnesium, the 

 former predominating, while sulphates are present only in 

 small amount. If now we compare this composition, which 

 may be regarded as representing that of the palaeozoic sea, with 

 that of the modern ocean, we find that the chloride of calcium 

 has been in great part replaced by common salt, a process 

 involving the intervention of carbonate of soda, and the for- 

 mation of carbonate of lime. The amount of magnesia in the 

 sea, although diminished by the formation of dolomite and 

 magnesite, is now many times greater than that of the lime ; 

 for so long as chloride of calcium remains in the water, the mag- 

 nesian salts are not precipitated by bicarbonate of soda.* 



When we consider that the vast amount of argillaceous sedi- 



* See Report Geol. Surv. Canada, 1857, pp. 212-214 ; Am. Jour. Science 

 (2), XXVIII. pp. 170, 305 ; and further, Essays VIII. and IX. 



