Treatise on Poisons by Sir Robert Christison

OF POISONING WITH MERCURY. The next genus of the metallic poisons includes the preparations of mercury. Some of these are hardly less important than the arsenical compounds. They act with equal energy, produce the same violent symptoms, and cause death with the same rapidity. They have therefore been often given with a criminal intent; and have thus become the subject of inquiry upon trials. In another respect, too, they claim the regard of the medical jurist: their effects on the body, when insidiously introduced in the practice of the arts in which mercury is used, form a branch of that department of medical police, which treats of the influence of trades on the health. SECTION I.—_Of the Chemical History and Tests for the preparations of Mercury._ Mercury is a fluid metal, exceedingly brilliant, of a silver-white colour, and of the specific gravity 13·568. When heated to about 660° F. it sublimes, and on cooling it condenses unchanged. If this experiment is made in a small glass tube, the metal forms a white ring of brilliant globules, which may be made to coalesce into a single large one. In this way its physical properties may be recognised, though the quantity is exceedingly minute. Two oxides of this metal, a protoxide and peroxide, exist in combination with acids. A bluish-gray or grayish-black protoxide is separated from the salts of the protoxide by the fixed alkalis. The peroxide has an orange-red colour, and is the common red precipitate of the apothecary. Mercury unites with sulphur in two proportions. The proto-sulphuret, which is black, is formed from the salts of the protoxide by the action of sulphuretted-hydrogen: the bisulphuret is the well known pigment, cinnabar or vermilion. Mercury likewise unites with chlorine in two proportions, forming an insoluble protochloride and a soluble bichloride, the former calomel, the latter corrosive sublimate. It likewise unites with cyanogen. Mercury also unites in the state of protoxide and peroxide with the acids. Several compound salts are known to the chemist, but few occur in commerce or the arts. Among the compounds resulting from the action of this metal with other substances, those which require notice in a toxicological treatise are the following:—1. The binoxide or _red precipitate_; 2. The bisulphuret or _vermilion_; 3. The protochloride or _calomel_; 4. The bichloride or _corrosive sublimate_; 5. The sulphate or _Turbith mineral_; 6. The _bicyanide_ or prussiate of mercury; and 7. The _nitrates_ of mercury. Its other compounds are of little consequence to the toxicologist.