as adhering to the walls, will be so arranged, as to resemble the 

 pipes of an organ ; and, on being struck by any hard substance, 

 will contribute to the delusion by sending forth a dull, bu.t ringing, 

 musical sound. The grotto of Antiparos ; the Baumannian cave in 

 the neighbourhood of Blankenberg ; the caves in the Hercynian 

 forest ; the grottoes of Arcy, in France ; of Chaumont, in- Nor- 

 mandy ; those astonishing natural excavations in Derbyshire, and 

 various others, may be considered as so many laboratories in which 

 nature is discovered, in her deep and secret recesses, unintermittingly 

 employed, separating, from the rude materials, the finer species of 

 stone, and amassing it in vast and inexhaustible stores. 



To ascertain the circumstances, on which the deposition of the 

 calcareous earth from different waters, immediately*depends, would 

 require a careful analysis of the separated matter, .of the waters, 

 from which the deposit is directly made, and of the different tribu- 

 tary streams ; as well as an examination of the strata through which 

 they pass, and the various circumstances under which they flow. 

 But, in this place, it will be sufficient to point out to your notice, 

 those properties of this earth, by which its solubility in water, and, 

 consequently, its precipitation, will be chiefly affected. 



Lime, in its pure state, is soluble in about 700 times its weight 

 of water, at the temperature of 60, and thus forms Common lime- 

 water; but if to this a small portion of carbonic acid be added, it 

 unites with the lime, forms a carbonate of lime, and precipitates in 

 an insoluble state. If, on the contrary, such a quantity of car- 

 bonic acid be added as will completely saturate the lime, it is again 

 rendered soluble in water; and it is thus that carbonate of lime, 

 held in. solution, by an excess of fixed air, not in actual combina- 

 tion with the lime, but contained in the water, and acting as a 

 menstruum, is commonly found in all waters *. A separation of 



* Analysis of Mineral Waters, p. 1 5. 



