In a state of minute division, it has been ascertained that, in the presence of an alkaline chloride and air, mercury is very slowly converted into corrosive sublimate; the metal probably being first oxidized, and the reaction then taking place between the mercurial oxide and the alkaline chloride. Hence we may account for the influence of the metal, taken internally or applied externally in a state of very minute mechanical division, or inhaled into the lungs or brought into contact with the skin, in the state of vapour.

In its ordinary metallic state, the metal is quite inert. it has been given in quantities varying from an ounce to a pound or more, in obstruction of the bowels, which it is said to have sometimes overcome simply by its weight; the metal passing away per anum unchanged. But at best it is an exceedingly uncertain remedy, and, in a case of irremovable obstruction, might remain in the bowels to the serious detriment of the patient. When long retained in that way, it has been known to produce very powerful if not fatal mercurialization, no doubt through chemical reaction between its particles, more or less minutely divided among the contents of the bowels, and any chloride of sodium or other chloride present.

It is in that state of minute division, produced by rubbing mercury up with other substances, that the metal is exhibited for its effects on the system. The ordinary metallic appearance is lost in the process, and the metal is said to be extinguished. it has been ascertained that a very minute proportion of oxide is produced, which is increased by time : but there is no reason to suppose that the effects of the medicine are to be wholly or even chiefly ascribed to this oxide; for the metal thus divided is known to be rendered slowly soluble, like the other insoluble mercurials, and a quantity of the oxide, prepared in other modes, equal to that contained in these preparations, would occasion no observable effect. The following are the preparations containing the mercury in minute division.