Calomel


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calomel

[′kal·ə·məl]
(mineralogy)
Hg2Cl2 A colorless, white, grayish, yellowish, or brown secondary, sectile, tetragonal mineral; used as a cathartic, insecticide, and fungicide. Also known as calomelene; calomelite; horn quicksilver; mercurial horn ore.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Calomel

 

(from the Greek kalos, “beautiful,” and melas, “black”), mercurous chloride, Hg2Cl2; a colorless powder. When treated with caustic alkalies or ammonia, it turns black (hence the name). The darkening occurs as result of the precipitation of finely powdered mercury according to the reactions

Hg2Cl2 + 2NaOH - Hg + HgO + 2NaCl + H2O

Hg2Cl2 + 2NH 4OH = HgNH2Cl + Hg + NH4C1 + 2H2O

Calomel has a density of 7, 160 kg/m3 and evaporates without fusion. Its sublimation point is 383.7°C. It is poorly soluble in water.

Calomel is used in the preparation of calomel electrodes and as a catalyst in organic reactions. In medicine it serves as an antibacterial agent, applied externally in ointment form in cases of wart infections and gonorrheal conjunctivitis and as a safeguard against venereal diseases (locally). Calomel is sometimes used internally as a cholagogue.

In nature calomel exists as a rare mineral of the halide group.It crystallizes in the tetragonal system and has an adamantineluster. Its hardness on the mineralogical scale measures 1.5.Native calomel exhibits very high double refraction. It is formedin the oxidation zone of mercury deposits.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
A three-electrode cell was used for electrochemical measurement which consists of coated substrate, platinum sheet, and saturated calomel electrode (SCE) as working electrode, counter electrode, and reference electrode, respectively, and 3.5 wt.% NaCl solution was used as corrosive electrolyte.
Briefly, quantitative studies of Cr(VI)-thymoquinone complex were performed at glassy carbon electrode against saturated calomel electrode which include determination of [E.sup.[omicron]], D, [alpha], and [beta].
% NaCl) into which the shrouded SPR assembly wasimmersed as working electrode 1 (WE-1), as well as the saturated calomel reference electrode (SCE).
(22) Rout opened a "soldiers' medical club" at Hornchurch in London, near a New Zealand convalescent hospital, sold prophylactic kits (these included calomel ointment, condoms and Condy's crystals) and gave advice.
Here tungsten ions implanted graphite substrate was used as working electrode, Graphite as counter electrode and the KCl saturated Calomel as a reference electrode.
The coated Al alloy in the middle layer acts as the working electrode, a saturated calomel electrode as the reference, and a platinum electrode as the counter.
Graphite electrode and saturated calomel electrode were used as counter electrode and reference electrode, respectively.
Though unstated in the official record, Hammond's real "crime" was his removal of calomel and tartar emetic from the Standard Supply Table, showing how decidedly hidebound his colleagues were to the old--even dangerous--remedies of the past.
A typical three-electrode experimental cell equipped with a working electrode, a platinum foil counter electrode, and a saturated calomel reference electrode (SCE) was used for measuring the electrochemical properties of the working electrode and its performance as a Faradaic electrochemical capacitances (ECs).
Electrochemical characterization of the mixed-culture anode was carried out with cyclic voltammetry (CV) using a CHI660D workstation (Shanghai CH Instrument Company, China) with a three-electrode system, where the biofilm-attached anode served as the working electrode, saturated calomel electrode (SCE) as the reference electrode, and the cathode as the counter electrode.
Electrochemical assay was performed on a CHI 660B electrochemical analyzer (Chenhua, Shanghai, China) with a conventional three-electrode system comprised of platinum wire as the auxiliary electrode, saturated calomel electrode (SCE) as the reference electrode, and glass carbon electrodes (GCE) as the working electrode.