3. (Caron.) Fused chloride of calcium in powder, 300 parts; distilled
zinc, finely granulated, 400 parts; sodium, in small pieces, 100 parts;
the whole placed in a crucible and heated to redness in an ordinary
furnace. The action is very feeble at first, but after some time zinc
flames arise. The heat must now be moderated to prevent the volatilisation
of the zinc, but at the same time it must be maintained as high as
possible. When the crucible has remained in this state for about a quarter
of an hour it may be withdrawn. On cooling, a metallic button will be
found at the bottom. This alloy of zinc and calcium, which generally
contains from 10 to 15% of the latter metal, must be placed in a coke
crucible and heated until the whole of the zinc is driven off. The alloy
should be in pieces as large as possible. When proper precautions have
been observed a button of CALCIUM is obtained, only contaminated with the
foreign metals contained in the zinc.
_Prop., &c._ The metal belongs to the group which includes BARIUM,
STRONTIUM, and MAGNESIUM; it is of a light yellow colour; is rather harder
than lead, and very malleable. It melts at a red heat. It tarnishes in a
day or two, even in dry air, and in contact with moist air it breaks up
like ordinary lime. Its sp. gr. is 1·55.
_Tests._ Salts of calcium in solution produce a white precipitate with
carbonate of ammonium; it becomes far less voluminous on heating the
solution, and dissolves very readily in hydrochloric acid. Sulphuric acid,
when added to concentrated solutions, gives an immediate white
precipitate; if the solution is not concentrated, the precipitate may
separate gradually, in minute crystals; and if it is very dilute, no
precipitation will take place, because sulphate of lime is soluble in
about 500 times its weight of water. With neutral solutions, even when
very dilute, oxalate of ammonium gives a copious white precipitate,
soluble in most dilute acids.
=Calcium, Acetate of.= Add prepared chalk to acetic (or purified
pyroligneous) acid till fully saturated; filter and evaporate, that
crystals may form. Diuretic. _Dose_, 10 to 20 grains.
=Calcium, Acid Phosphate of.= _Syn._ SUPERPHOSPHATE OF LIME, SOLUBLE ACID
PHOSPHATE. CaH_{4},2PO_{4}. This may be procured by treating bone-earth
with two thirds of its weight of oil of vitriol, as in the preliminary
stage of the extraction of phosphorus. It is extensively used as a manure
for turnips.
=Calcium, Bibasic Phosphate.= Ca_{2}H_{2}P_{2}O_{8} + 3H_{2}O. Dissolve
608 grams of crystallised calcium chloride in 1000 grams of distilled
water, and add gradually to this solution 1000 grams of sodium phosphate,
dissolved in 10,000 grams of water. Allow the precipitate to deposit, and
wash it five or six times with 10 litres of water each time; drain the
precipitate on a moistened cloth. As soon as its consistence permits,
detach from it irregular pieces, and place them to dry in the open air
upon filtering paper; the spontaneous desiccation is sufficiently rapid.
From 'Formulæ for New Medicaments adopted by the Paris Pharmaceutical
Society.'
=Calcium, Bro'mide of.= CaBr_{2}. _Syn._ CAL'CII BROMI'DUM, L. _Prep._
(Magendie.) To a solution of bromide of iron add hydrate of calcium in
slight excess; filter, evaporate to dryness, redissolve in water, and
again filter, and evaporate.
=Calcium, Carbonate of.= See CHALK.
=Calcium, Chlo''ride of.= CaCl_{2}. _Syn._ CAL'CII CHLORI'DUM (B. P.).
_Prep._ Hydrochloric acid and water, of each 10 fl. oz.; chalk, 5 oz.;
evaporate the solution until the salt becomes solid, and dry the residue
at about 400° F.
It is obtained in solution as a residuum in making several preparations of
ammonia, as the liquor and carbonate, and in making carbonic acid by the
action of hydrochloric acid on marble. The residuum is concentrated and
set aside to crystallise, or evaporated to dryness.
_Prop., Uses, &c._ This salt crystallises in colourless, striated,
hexagonal prisms, terminated by very acute points. It is very soluble in
alcohol and water, the latter even at 32° dissolving more than its own
weight, and at 60° three or four times its weight of this salt. When
heated, the crystals undergo watery fusion. When dissolved in water, they
produce great cold; and hence are frequently employed as an ingredient in
FREEZING MIXTURES. These crystals contain nearly half their weight of
water. They are very deliquescent, passing readily into the liquid state,
and forming what used to be called oleum calcis, or oil of lime. The
anhydrous chloride is hard and friable; slightly translucent; totally and
readily soluble in water, and, like the crystallised salt, very
deliquescent. In the laboratory chloride of calcium, either fused or
merely dried, is continually used for drying gases and for absorbing the
water from ethereal and oily liquids in organic analysis. The unfused is
now generally preferred for this purpose, as it is more porous than the
fused. The salt is also used in the rectification of alcohol, and to form
a bath for heating stoneware stills and other apparatus liable to be
cracked on the sand bath. As a chemical reagent it is employed chiefly in
detecting certain organic acids. As a medicine it has been given in some
scrofulous and glandular diseases. _Dose_, 10 to 20 gr. See SOLUTIONS.
=Calcium, Flu'oride of.= CaF_{2}. _Syn._ HYDROFLU'ORATE OF LIME. This
occurs native as the mineral called fluor-spar. It is found in beautiful
crystals in the lead mines of Alston Moor and Derbyshire, and in the
concretionary crystalline masses known as Blue John or Derbyshire spar at
Castleton. It may be prepared by the action of hydrofluoric acid upon
lime, as directed under BARIUM, FLUORIDE OF.
=Calcium Hypophosphite.= CaP_{2}H_{4}O_{4}. Mix milk of lime (1 in 5) in
porcelain capsule placed in a sand bath, with half its weight of
phosphorus in small pieces, and heat it to ebullition, operating in the
open air or under a chimney with a good draught. Spontaneously inflammable
phosphuretted hydrogen is given off, the vapour of which should be
avoided. Add from time to time a little warm water, to replace that which
has evaporated. Discontinue the heat when the phosphorus has
disappeared--that is, when inflammable bubbles cease to be produced. If
the phosphorus remain in excess, add more milk of lime, and continue the
heat until the complete disappearance of the metalloid. Allow the liquor
to cool and then filter; then saturate it with a current of carbonic acid
gas to eliminate any excess of lime remaining uncombined. Filter again,
and concentrate the liquor in a water bath to dryness, keeping the
temperature below 100° C., to avoid detonations. Preserve the salt from
the air in well-closed bottles.
From 'Formulæ for New Medicaments adopted by the Paris Pharmaceutical
Society.'
=Calcium, I'odide of.= CaI_{2}. _Syn._ HYDRI'ODATE OF LIME; CAL'CII
IODI'DUM, CALCIS HYDRIO'DAS, L. _Prep._ 1. (Magendie.) From a solution of
protiodide of iron and hydrate of calcium, as directed under iodide of
barium.