82 CHEMISTRY OF LIMESTONES AND DOLOMITES. [VIII. 



In the American Journal of Science for 1859 will be found 

 the results of a series of investigations of the reactions of 

 solutions of bicarbonate of soda with sea-water, and upon the 

 conditions required for the precipitation of carbonate of mag- 

 nesia and the formation of dolomite. I have there also shown 

 the mutual decomposition, at ordinary temperatures, of solutions 

 of bicarbonate of lime and sulphate of magnesia, resulting in 

 the formation of gypsum and of a soluble bicarbonate of mag- 

 nesia, which becomes the source of dolomite or of magnesite. 

 A notice of the first part of these researches will be found in 

 the Comptes Rendus for May 23, 1859. In the continuation 

 of them, as cited above, it is shown that the association of mag- 

 nesian and pure limestones establishes the fact that these rocks 

 have both been deposited as sediments, and that the hypothesis 

 which explains the origin of dolomites by a subsequent altera- 

 tion of pure limestones is inadmissible. It is also shown that 

 great portions of limestone, even in fossiliferous formations, 

 have the characters of precipitates resulting from chemical re- 

 actions, and have never formed part of organized beings ; which 

 last, moreover, owe their carbonate of lime to similar reactions. 



My views upon the composition of the primitive ocean were 

 further supported by the analyses of numerous saline waters 

 from lower pala?ozoic limestones. In these waters, the bases of 

 which are almost wholly in the condition of chlorides, about 

 one half of the chlorine is combined with sodium, and the 

 other half is nearly equally divided between calcium and mag- 

 nesium. 



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 J><T- 

 fect accordance. It will further be observed, that the publica- 

 tion of Mr. Leymerie, in which similar views are, to a cer- 

 tain extent, indicated (see the Comptes Rendus of March 10, 

 1862), dates only from 1861, while my own papers apj- 

 in 1858 and 1859. 



My researches upon the origin of dolomites and limestones 

 fully justify the previsions of Mr. Corlicr. Hi-. Imwi-vi-r, in 



