"The well-known manufacturing chemist, E. Merk, in Darmstadt, has
heretofore prepared and sold a substance which was supposed to be the only
active principle of calabar, and which he called calabarine, but which was
really eserine or physostigmine. He now accepts and confirms the results
of Harnack's and Witkowsky's researches, and has put both of the active
principles upon the market labelled with their correct name, viz.
'_Physostigmin_' (or eserine, being the same substance which he formerly
sold as calabarine), and '_Calabarin_,' distinguished by the addition of
Harnack's name (Harnack's 'Calabarine'). _The attention of physicians and
pharmacists is particularly directed to the change of appellations._"
Calabar bean is a powerful poison. The antidotes are:--Diffusible
stimulants; the hypodermic injection of the 1/50th of a grain of sulphate
of atropia, to be repeated if necessary at the end of two hours; and
artificial respiration. See ESERINE.
=CAL'AMINE.= See ZINC (Carbonate of).
=CALCINA'TION.= The operation of burning or roasting any solid body to
expel its more volatile parts, as the conversion of chalk into lime by the
expulsion of carbonic anhydride. The roasting of the ores in the first
stage of the Welsh process of copper smelting and in the Silesian mode of
extracting zinc is technically termed CALCINATION.
The method of conducting the process of calcination depends on the nature
of the body operated on. Many substances, for delicate experiments, are
calcined over a spirit lamp in a platinum spoon or crucible; others, in
iron vessels or earthen crucibles, placed in a common furnace. When the
action of the air proves injurious, as in the manufacture of charcoal, the
process is performed in close vessels or chambers. In some cases the fuel
is mixed with the articles, and they are both burnt together, as in the
manufacture of lime, the roasting of ores, &c. The process of drying
salts, or driving off their water of crystallisation by heat, is also
frequently called CALCINATION; thus we have calcined copperas, alum, &c.
=CAL''CINER.= A reverberatory furnace used for the calcination of metallic
ores, particularly those of COPPER and ZINC (which _see_).
=CAL'CIUM.= [Eng., L.] Ca. The metal of which LIME is an oxide. Though it
is a chemical curiosity when isolated, it is one of the most abundant
substances in nature, forming a very large portion of the crust of the
earth. It occurs in combination with fluorine as fluor-spar; with oxygen
and carbonic acid as chalk, limestone, and marble; and with oxygen and
sulphuric acid as gypsum. The metal was first obtained from lime by Sir H.
Davy in 1808; but little was known of its properties until Dr Matthiessen
formed it by the electrolytic decomposition of the chloride of calcium.
_Prep._ 1. By the action of a powerful voltaic current upon a paste of
pure lime in contact with mercury, as in the original method of preparing
barium.