MERCURY—is become an article of so much medical utility with HORSES, as well as with the human species, that it seems entitled to some mention here, being a specific much talked of, but not universally understood. Mercury (alias quicksilver) is an opaque silver-colored mineral fluid, appearing to the eye like melted TIN or LEAD; it is heavier than any other fluid, and does not congeal in the greatest degree of natural cold ever yet known. This mineral is met with in its fluid form in the earth, or extracted by art from certain metallic ores. There are considerable mines of it in HUNGARY and SPAIN; but the greatest quantities are brought from the EAST INDIES. The use of mercury was but little known till within the last century; and its more subtle preparations, with their efficacious properties, of a much later date. The ancients looked upon it as a confirmed corrosive poison, though perfectly void of acrimony, taste, and smell. Experiments have been made, and instances proved, of its having been lodged for years in cavities of both bones and fleshy parts, without the least injury, or smallest sensible or perceptible effect. Taken into the human body in its crude and undivided state, it passes through the intestinal canal unchanged, and has not been found to produce the least inconvenience. Notwithstanding the _mildness_ and _inactivity_ of QUICKSILVER in its crude and undivided state, yet, when resolved by FIRE into FUME, or otherwise divided into very minute particles, and prevented from re-uniting by the interposition of proper substances, or combined with mineral acids, it has very powerful effects, affording the most violent POISONS, and yielding the most excellent and salutary remedies, of any with which the medical world are acquainted. There are now (introduced upon the broad basis of experimental practice) a variety of mercurial preparations, some of which are given internally; others are introduced (or rather insinuated) into the habit by external application, either in a liquid solution, or in an unctuous form: in whatever way it be administered internally, or applied externally, it evidently possesses the power of solving all stagnant fluids, liquifying the viscid juices which obstruct the finer vessels, and most minute passages; and has been known, by patient perseverance, to obliterate cancerous affections, and schirrosities of dangerous magnitude. The fundamental effects of mercury (or rather mercurial preparations) do not depend upon the increase of the sensible evacuations; as its gradual introduction into the habit (or system) of either man, or beast, may be so managed, by judicious proportions, as to promote excretion through the different emunctories, without perceptibly deranging the frame of one or the other.