mercurous chloride

mercurous chloride   mercury (I) chloride, or calomel, chemical compound, Hg ₂ Cl ₂ , a white crystalline powder, very slightly soluble in water. It was once used medicinally as a purgative, cathartic, liver stimulant, and to eliminate parasitic worms, but is rarely so used today because it is readily decomposed into metallic mercury and the very poisonous mercuric chloride on exposure to sunlight or if heated in the presence of moisture. Mercurous chloride is a less dangerous poison than mercuric chloride chiefly because it is much less soluble; it is highly toxic if retained in the body. Mercurous chloride is prepared by sublimation from a mixture of mercury and mercuric chloride or by precipitation from a mercurous chloride solution on adding chloride ion. It is also found in nature as horn quicksilver. The calomel electrode, often used as a reference in determining electric potentials and for measuring the p H of solutions, contains mercurous chloride, mercury metal, and potassium chloride solution.

mercuric chloride or mercury (II) chloride, chemical compound, HgCl ₂ , a white powder of colorless rhombohedral crystals, somewhat soluble in water. It is also called bichloride of mercury or corrosive sublimate. It is extremely poisonous. Raw egg white may be given as an antidote, since mercuric chloride reacts with egg albumin to form a nearly insoluble precipitate; medical treatment should be sought immediately. Mercuric chloride is sometimes used in dilute solution as an antiseptic for inanimate objects and as a fungicide. It is also used in preparing other mercury compounds; it reacts with mercury metal to form mercurous chloride . Mercuric chloride is prepared by reacting mercury with chlorine gas or by subliming a mixture of mercuric sulfate and sodium chloride (common salt).