163 



of soda in the above analyses. Bromine and iodine are found in all 

 the saline waters. I have shown, in my analyses of five alkaline 

 saline waters from Caledonia and Varennes, that the amount of 

 carbonic acid is much less than is required to form bicarbonates 

 with the soda, lime and magnesia which these waters contain, so that 

 the magnesia must be held dissolved as a mono-carbonate. In the 

 water of Chambly, on the contrary, there is no deficiency of carbonic 

 acid, and the bases exist as bicarbonates. The temperatures of these 

 springs range from 46 to 53 F. ; some of them are therefore to be 

 regarded as slightly thermal. 



Interstratified with the shales and sandstones of the Quebec divi- 

 sion of the Lower Silurian rocks, which immediately overlie the 

 strata yielding these alkaline waters, are found thick beds of pure 

 limestone, sometimes presenting the agatized structure and semi- 

 translucency which characterize certain travertines, but at other 

 times opaque, homogeneous, and including remains of orthoceratites, 

 trilobites and other fossils; Associated with these beds of pure car- 

 bonate of lime are others which are magnesian, and contain con- 

 siderable quantites of carbonate of iron, which causes them to 

 weather reddish brown. These beds are always granular in texture, 

 and contain a variable portion of siliceous sand ; they often become 

 conglomerate, enclosing pebbles of quartz and schist, or more fre- 

 quently fragments of a pure compact limestone, seemingly identical 

 with that of the beds just described. Thin layers of the ferruginous 

 magnesian rock sometimes separate beds of the pure carbonate of lime, 

 or form lenticular masses in its midst, and seem to replace its fossils. 

 The pure limestones also sometimes form the base of a conglomerate, 

 or are mixed with sand and argillaceous matters. 



These magnesian rocks, like the pure limestones of this formation, 

 occur in irregular and interrupted beds ; they often attain a thick- 

 ness of many yards, are destitute of fossils, and contain from ten to 

 forty per cent., and even more, of sand or clay. The portion soluble 

 in acids is sometimes a dolomite with carbonate of iron ; at other 

 times the lime is wanting, or present only in traces, and we have a 

 ferruginous magnesite. In two previous notes presented to the 

 Society, I have already explained the manner in which I suppose 

 these siliceous carbonates to have been, in some parts of the forma- 



