COMMON LIME. CHALK. 99 
state of solution, and in the proportion of half a pound 
of quick-lime to twelve pints of boiling distilled water. 
This preparation is called lime water. 
The superb basin of Lampi, one of the principal re- 
servoirs which furnishes the canal of Languedoc with 
water, was, some years ago, found to leak at the junc- 
tion of the stones. The engineer who had the direction 
of the works caused lime to be slacked in the water. 
This, passing through the apertures betwixt the stones, 
formed a crust, or very white covering, over its whole 
surface, of so hard and durable a nature, that it now 
constitutes one solid and undivided substance, which 
the water cannot penetrate* 
CARBONAT OF LIME. 
140. COMMON LIME is a variety of carbonat of lime, 
or of lime in combination with carbonic acid (26), which is 
harder and heavier than chalk., usually of a greyish colour, and 
is always found hi a massive state. 
Vast mountains of limestone occur in several coun- 
tries of the globe ; but no where is lime more abundant 
than in some parts of England and Wales. It forms, 
in particular, nearly the whole mountainous districts of 
Derbyshire and Shropshire, and encloses, in its sub- 
stance, numerous veins of lead ore, calamine, and other 
important mineral productions. 
Its uses have been already described (139). 
141. CHALK is a white or yellowish kind of limestone, too 
well known to need any description. 
It is found abundantly in many of the southern coun- 
ties of England, and is usually procured from large 
open places, called chalk-pits, by digging. In some 
parts of Kent, however, the workmen save themselves, 
in this respect, much trouble. They undermine the 
sides of hills to a certain depth, then dig a trench at 
the top as far distant from the edge as the mining ex* 
tends at the bottom. This trench they fill with water, 
which soaks through during the night, and the whole 
F 2 
