Symbol

Hg. Sp. gr. 13.5.

Sources

Mercury is a metal of a nearly silver-white color, and a very high degree of lustre. It is liquid at all ordinary temperatures, and only solidifies when cooled to 390 or 400 F. It boils at about 66o° F., it is malleable at 400 F., and is slightly volatile at 6o° F.; when boiling it yields a transparent, colorless vapor, of density of 100. It also volatilizes somewhat even at ordinary temperatures, and especially above 68° F. The ordinary ore from which metallic mercury is obtained is the mercuric sulphide, although it is occasionally met with in globules disseminated through this native sulphide. There is also a form known as horn silver, or native calomel, and a native amalgam of silver and mercury. California furnishes metallic mercury of a peculiar purity, in large quantities. The metal is obtained from the sulphide by the process of "roasting." When pure, metallic mercury does not readily tarnish in the air, and has neither taste nor smell, and it can be purified by re-distillation, or by adding to it a small quantity of a strong solution of nitrate of mercury.

The impurities are generally dirt, dust, lead, tin, bismuth or zinc. The tarnishing of mercury implies the presence of other metals.

It is used as mercury in medicine in the form of ointment, plaster, gray powder, and blue mass. All preparations of mercury yield to absorption and after absorption to elimination, the rapidity of both depending to a great extent on the variety of it given. According to Prof. H. C. Wood, a single dose of mercury does not remain in the system, but when the drug is administered constantly for a length of time, the elimination does not keep pace with the absorption, so that the mercury accumulates in the tissues; also that the elimination is irregular and inter-mittent, and there is no limit of time during which the accumulated mercury may remain in the body, and that all probabilities point to the possibility of mercury being deposited in the tissues in such a form that it is practically inert and exerts no effect upon the system; it is liable however, under certain agencies, to be set free and to exert its power upon the general nutrition.

Dental Uses

Metallic mercury is employed in dental practice as an ingredient of amalgam filling material, being combined for such a purpose with silver, tin and zinc, and sometimes with gold and platinum, in addition to the other metals named.

Hydrargyri Chloridum Corrosivum

Corrosive Chloride of Mercury - Corrosive Sublimate. Mercuric Chloride, Bichloride of Mercury. Formula, HgCl2.

Derivation

Corrosive sublimate is obtained by subliming a mixture of chloride of sodium and mercuric sulphate, the latter made by boiling together sulphuric acid and mercury; double decomposition takes places, forming mercuric chloride and sulphate of sodium. Corrosive sublimate is in the form of colorless crystals, or crystalline masses, which are inodorous, fusible and sublime without residue, and of an acrid, styptic taste. It is readily soluble in 15 parts of water, 7 parts of alcohol and ether.

Medical Properties And Action

It is one of the most active salts of mercury, and is a corrosive poison, but the therapeutic dose now used is less liable to cause the disagreeable and dangerous effects of mercury than almost any other preparation employed for the same purposes. It is in the form of colorless crystals, and is entirely soluble in water. Corrosive sublimate is an effective germicide in the strength of one part to 2500 parts of water, being 250 times more powerful than carbolic acid. An aqueous solution of I in 20,000 destroys the spores of bacilli in ten minutes, and a solution of 1-5000 is a certain disinfectant, when the exposure is very short, and it is now regarded as one of the most powerful germicides in use and is very extensively employed in antiseptic surgery ; but it should be noted, however, that where albumen is present the bichloride is decomposed and rendered inert. The same occurs when solutions are permitted to stand for some time even when distilled water is used as a solvent. The addition of a weak acid, tartaric, or chloride of sodium, will prevent such decomposition. The bichloride, according to Koch, is efficacious as a germicide in a watery solution of 1 - 50,000.

Dr. F. Abbott regarded the bichloride of mercury as being the simplest antiseptic in use. Dr. W. D. Miller, of Berlin, also testifies to the power of the bichloride as an antiseptic in the treatment of the oral cavity as follows: "The experiments show that bichloride of mercury is about two hundred times as powerful as carbolic acid, and demonstrate very clearly the mistake of substituting weak solutions of this antiseptic (1 - 1000, as I have seen recommended) for concentrated carbolic acid. One one-thousandth is only one-fifth as powerful as pure carbolic acid, which in many cases may be used with impunity. It is consequently useless to attempt to introduce the sublimate solution for the purpose of sterilizing root-canals, cavities before filling, etc., unless we may use at least a 1/2 per cent., if not a one per cent. solution. I see no reason why this may not be done. In a few cases I have used a 1 per cent. solution for treating root-canals, and do not hesitate, particularly with the rubber dam adjusted, to wipe out cavities before filling with a two per cent solution, and see no possible evil which would result from it." "As a mouth wash I have frequently used a 1 per cent. (1.000) solution myself, and have seen no bad results from it; I would not, however, recommend it to my patients in this strength."

The solution in water, 1 part to 2000, will approximate I grain to 4 1/2 ounces of water.

Dr. Black recommends the following combination: Mercuric chloride, gr. ij; peroxide of hydrogen, Medical Properties And Action 1080 M. For use as an injection in alveolar abscess and the pus pockets of pyorrhoea alveolaris. As a solution of bichloride of mercury is prone to •undergo chemical changes, powders or tablets containing equal quantities of the bichloride and ammonium chloride may be prepared and a solution made by adding one of these to an ounce of distilled water.