2^4 Dr, Hunt on the Chemistry of the Earth, 



farther supported by the analyses of nuraerous saline waters from 

 Lower Silurian limestones. In these waters, the bases of which 

 are almost wholly in the condition of chlorids, about one-half of 

 the chlorine is combined with sodiura, and the other half is nearly 

 equally divided between calcium and magnesium. 



The Academy will perceive from the short analysis above given, 

 the extent and the importance of my generalizations, with which 

 the ideas of Mr. Cordier are, for the most part, in perfect accord- 

 ance. It will farther be observed, that the publication of Mr. 

 Leymerie, in which similar views are, to a certain extent, indi- 

 cated, (see the Comptes Rendus of March 10, 1862,) dates only 

 from 1861, while my own papers appeared in 1858 and 1859. 



My researches upon the origin of dolomites and limestones fully 

 justify the previsions of Mr. Cordier. He however, in his theory, 

 excepted the limestones of primitive formations, but these are 

 known to modern geologists to be nothing more than metamor- 

 phosed sedimentary formations, and consequently offer no excep- 

 tion to the general view. The different sources of carbonate of 

 soda indicated by Mr. Cordier, may moreover be reduced to a 

 single one, inasmuch as both the salts of alkaline springs, and those 

 of what he calls plutonic emanations, are probably derived from 

 the decomposing feldspathic minerals of sedimentary rocks. The 

 argillaceous rocks, deprived of a large proportion of the alkali 

 which they once contained in the form of feldspars, are the equiv- 

 alents of the limestones which have been formed at the expense 

 of the chlorid of calcium of the primitive ocean. 



The waters of certain rivers contain alkaline carbonates, in some 

 cases with notable proportions of silica and potash ; an example 

 of this is found in the water of the Ottawa. The presence of 

 silica and potash in river waters appears to be in great part due 

 to the soluble matters derived from the decomposing vegetation 

 of peat bogs, for in the waters of deep-seated springs, both neu- 

 tral and alkaline, the salts of potash are generally found in very 

 minute quantities. This is not surprising \^hen we consider the 

 great stability of potash-feldspar, and also the power which alum- 

 inous soils possess of removing silica and potash from infiltrating 

 waters, and of replacing the latter by soda. Atmospheric waters thus 

 dissolve from sediments only the soda, lime and magnesia which 

 these contain, and, with the intervention of organic matters, oxyd 

 of iron, and sometimes oxvd of mano-anese. It results from these 

 affinities that the sediments which are most silicious, and conse- 



