LIME. 
437 
Bok II. 
then is a simple substance, and limestone is composed 
of carbonic acid and lime. Heat separates the carbonic 
acid, and leaves the lime in a state of purity. 
When lime is exposed to the open air, it gradually 
attracts moisture, and falls to powder; after which it 
soon becomes saturated with carbonic acid, and is again 
converted into carbonat of lime or unburnt limestone. 
Lime 
Water, at the common temperature of the atmo 
water. 
sphere, dissolves about o.002 parts of its weight. This 
solution is called lime-water. It is limpid, has an acrid 
taste, and changes vegetable blue colours to green. One 
ounce troy of lime-water contains about one grain of 
lime. It is usually formed by throwing a quantity of 
lime in powder into pure water, allowing it to remain 
for some time in a close vessel, and then decanting the 
transparent solution from the undissolved lime. When 
lime-water is exposed to the air, a stony crust soon 
forms on its surface composed of carbonat of lime ; 
when this crust is broken it falls to the bottom and an 
other succeeds it ; and in this manner the whole of the 
lime is soon precipitated, by absorbing carbonic acid 
from the air. 
If lime-water be slowly distilled in a glass retort to 
dryness, and then more lime-water poured in, and the 
distillation repeated three or four times successively, 
the lime, according to Trommsdorff, may be obtained 
in crystals. 
Lime does not combine with oxygen, hydrogen, azot, 
carbon, nor charcoal ; but it combines with sulphur 
and phosphorus. 
Sulphuret of lime may be formed by mixing its two Sulphuret. 
component parts, reduced to a powder, and heating 
them in a crucible. They undergo a commencement