ature, but in combination with acids, chiefly the carbonic and
sulphuric. The phosphate occurs principally in bones. The hydrate and
the salts of lime are in their properties similar to those of the two
preceding alkaline earths. In the pure state, the oxide of calcium is
white; it slakes, produces a high temperature, and falls into a white
powder when sprinkled with a little water. It is now a hydrate, and
has greatly increased in volume. The hydrate of lime is far less
soluble in water than either those of baryta or strontia, and is less
soluble in hot water than in cold. Lime, its hydrate and sulphide of
calcium, have a strong alkaline reaction upon red litmus paper. Lime
and its hydrate are infusible, but produce at a strong red heat a very
intense and splendid white light, while the hydrate loses its water.
The carbonate of lime is also infusible, but at a red heat the
carbonic acid is expelled, and the residue becomes caustic, appears
whiter, and produces an intenser light. The sulphate of lime melts
with difficulty, and presents the appearance of an enamelled mass when
cold. By heating it upon charcoal it fuses in the reducing flame, and
is reduced to a sulphide. This has a strong hepatic odor, and exerts
an alkaline reaction upon red litmus paper. By exposing lime, or its
compounds, upon platinum wire--or as a small splinter of the mineral
in the platinum tongs--to the point of the blue flame, a purple color,
similar to that of lithia and strontia, is communicated to the
external flame, but this color is not so intense as that produced by
strontia, and appears mixed with a slight tinge of yellow. This color
is most intense with the chloride of calcium, while the carbonate of
lime produces at first a yellowish color, which becomes red, after the
expulsion of the carbonic acid. Sulphate of lime produces the same
color, but not so intense. Among the silicates of lime only the
tablespar (3CaO, 2SiO^{3}) produces a red color. Fluorspar (CaFl)
produces a red as intense as pure lime, and fuses into a bead.
Phosphate and borate of lime produce a green flame which is only
characteristic of their acids. The presence of baryta communicates a
green color to the flame. The presence of soda produces only a yellow
color in the external flame.

If alcohol is poured over lime or its compounds and inflamed, a red
color is communicated to the flame. The presence of baryta or soda
prevents this reaction. Lime and its compounds do n