ANNUAL ADDRESS, MDCCCLXXIII. 43 



by rivers holding it also chiefly in solution. The way in 

 which limestone gets into solution is as follows : Rain 

 water is of course not charged with mineral matter, but 

 it contains carbonic acid, which it carried with it whilst 

 being evaporated from the sea or other waters, as well 

 as an additional quantity which it absorbs during its 

 aerial sojourn. In this state it has considerable dissolving 

 power on carbonate of lime. Limestones are dissolved in 

 large quantites by it, as may be seen by the smoothed, 

 surface of the rocks when exposed to the weather: they 

 may be seen to be worn into fantastic shapes, and with 

 corals, stems of crinoids, and shells standing out in relief 

 because of their harder and more compact structure. In 

 this way the extensive caverns in the limestone formations 

 have been produced. The sea water having been shown 

 to be the great reservoir of limestone in solution, the 

 question arises, How does it become re-formed into rocks? 

 Professor Ramsay says that all the carboniferous limestone 

 owes it origin to marine life of various kinds, which sepa- 

 rated or secreted lime from the water. He states at p. 

 77 of his Physical Geology that the carboniferous lime- 

 stone is entirely formed of sea shells, encrinites, corals, 

 and other organic remains, and at p. 11, "In many a 

 formation, for instance, in some of the beds of the car- 

 boniferous limestone, the eye tells us that they are formed 

 perhaps entirely of rings of encrinites or stone-lilies, or of 

 shells and corals of various kinds, or of all these mixed 

 together ; and in many other cases where the limestone is 

 homogeneous the microscope reveals that it is made up 

 of exceedingly small particles of broken organic remains. 

 Even when these fragments are indistinguishable, reason 

 tells us that such marine limestone deposits must have 

 been built up of the debris of life, for there is no reason 

 to believe that vast formations of limestone, extending 



