370 On some Relations of the Salts of Lime and Magnesia, 
ments are black augite, mica and olivine, derived from the igne- 
nesia 16:4, carbonate of iron 25°8=100-0. In one instance these 
yellow-weathering beds of conglomerate are associated with 
others of which the cement remains white on the exposed sur- 
faces, effervesces freely with acids, and is pure carbonate of lime. 
— 1. 
there are drusy cavities lined with crystallized dolomite and oc- 
easionally containing prisms of quartz. The analysis of a frag- 
ment of the cast of an Orthoceras from the Trenton limestone at 
Ottawa, gave me carbonate of lime 56-00, carbonate of magnesia 
87-80, carbonate of iron 5-95=99:75. The surrounding lime- 
Stone, which was compact, bluish-gray, and bituminous, con 
