Abstract
Mercuric iodide is relatively insoluble in water but is easily soluble in an aqùeous solution of potassium iodide. The complex salt potassium mercuric iodide, having the formula K2HgI4, is formed by the interaction of one molecule of mercuric iodide (HgI2) with 2 molecules of potassium iodide (KI). The preparation contains about 25.5% of mercury.
Aqueous solutions of the salt have been extensively employed as disinfectants because they do not possess the corrosive action on instruments and tissues that characterizes aqueous solutions of mercuric chloride. Another advantage is that they do not precipitate albumin.
Potassium mercuric iodide is about one-half as toxic as mercuric chloride when administered to animals. In proportion to the mercury content, however, the 2 salts possess about the same toxicity.
In previous papers of this series 1-6 comparisons were made of the resistance of Staphylococcus aureus and embryonic chick heart tissue to phenol, Merthiolate, Metaphen, Mercurochrome, Hexylresorcinol, iodine, and iodine trichloride. Toxicity indices were determined by dividing the highest dilution of the germicide that killed the tissue by the highest dilution of the chemical showing no growth of the test organism. Theoretically the smaller the toxicity index the more nearly perfect the chemotherapeutic agent.
The methods employed were the same as those given in the first paper of this series. Wide jumps in the dilutions were first prepared to determine approximately the least concentration of the germicide required to destroy the bacteria in 10 minutes but not in 5 minutes. Usually one such preliminary series was sufficient. Occasionally a second series covering higher dilutions was necessary.
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