This earth is of a white colour, and of a hot caustic taste; with acids
it forms peculiar salts; a fact which we shall shew affords the most
decisive means of identifying its presence. It changes vegetable blues
to a green, and reddens _turmeric_; it is capable of fusion; so great is
its affinity for water, that it will absorb and solidify one third of
its weight of that fluid, and yet remain perfectly dry. The heat,
therefore, that is evolved in the process of slacking lime, evidently
proceeds from the water, which yields its caloric, as it passes from the
liquid to the solid state.
_Symptoms of poisoning by Lime._
It is perhaps the least energetic of the corrosive poisons; and yet,
when taken in any quantity, it will produce nausea, vomiting, colics,
frequent stools, and all the symptoms which characterise, or are
complicated with, inflammation of the stomach and intestines.[332] Lime
in combination with carbonic acid is not considered as poisonous.
_Organic lesions discovered on dissection._
In examining the body of an animal that has been killed by caustic lime,
we shall find the mucous membrane of the stomach reddened, and evincing
marks of inflammation in those parts which have been in contact with it.
_Tests for the detection of Quick-lime._
We may proceed, if the substance be free from mixture, to obtain a
solution of the earth in distilled water, and to assay it by the
following reagents.
(_a_) _Carbonic acid, and the soluble alkaline sub-carbonates_ produce a
copious white precipitate, which is soluble in an excess of carbonic
acid. The _carbonate of lime_, of which this precipitate consists, is
also decomposed by muriatic acid, with effervescence, a soluble muriate
remaining.
(_b_) _Oxalic acid, and oxalate of ammonia._ They precipitate lime-water
of a white colour, and the resulting _oxalate_ is not soluble in an
excess of acid.
(_c_) _Sulphuric acid._ This acid does not precipitate lime water, since
the _sulphate of lime_ formed does not require more than 300 parts of
water to dissolve it. Whereas, says _M. Orfila_, the smallest quantity
of an exceedingly diluted solution of _baryta_ becomes instantly turbid
on the addition of that acid, because the _sulphate of baryta_ is
insoluble in several thousand times its weight of water. By this test,
therefore, we are at once enabled to distinguish lime-water, from
barytic water.