373 
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, but 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 combi- 
nation 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. 15. 
