Professor Ramsay in a recent paper put forward the notion that the Magnesian Limestone and its associated beds of the north-east of England were formed, in part at least, by chemical precipitation in an inland sea. Given such a sea, without outlet, and with streams flowing into it holding in solution the necessary salts (bicarbonate of lime and sulphate of magnesia would answer the purpose), it is clear that by continued evaporation a state of saturation would at length be brought about, and precipitation would take place, and Dr. Sterry Hunt has shown that dolomite and gypsum would be the probable products.