inflammable, such as those arising from the solution of iron in the vitriolic acid, the operator ought never to approach the vessel with a candle, or other burning substance; as the exhaling vapour would thus instantly be set on fire, and cause an explosion.
Lastly, there is another species of solution, in which the moisture of the atmosphere is the menstruum. If fixed alkaline salts or earths, for instance, pot-ash, as well as the neutral salts composed of the former, and the vegetable or any other acids (except the vitriolic, and some metallic salts), be exposed for some time to a moist air, they gradually absorb humidity, and at length become liquid; a process which is termed deliquation.
MERCURY, or Quicksilver (Hydrargyrus), a mineral fluid, about fourteen or fifteen times heavier than water: it is so remarkably thin, that it requires the intense cold of 40 degrees below 0, of Fahrenheit's scale, to render it solid.—When exposed to fire, it may be totally volatilized.
Quicksilver is found sometimes in a native state, as in the mines of India, South America, Hungary, &c.; but more generally mixed with metals, stone, or other substances, from which it is extracted by various processes. Next to gold, and platina, mercury is the heaviest of all metals, with most of which it unites, excepting iron and antimony: hence it is employed in considerable quantities, for extracting gold and silver from the earthy matters with which they are mixed.—The amalgam, or incorporation of quicksilver with gold, serves to gild copper or silver, so that these metals assume the appearance of gold: when united with tin, it is employed in the manufacture of looking-glasses or mirrors, in the manner already described, p. 125 of the present volume.
Independently of its utility in various manufactures, mercury is extensively employed in medicine; and, though it is the most violent of poisons, when taken inadvertently in too large quantities, yet, if judiciously administered, it has frequently effected a cure, after all other medicines had failed to procure relief. When taken into the stomach undivided, or in its native state, this fluid metal almost instantly passes through the intestines unchanged, and produces no perceptible effect, except that of promoting evacuation, if any crudities or obstructions should prevail in the alimentary canal. Hence it might be advantageously prescribed in the first stage of the Iliac Passion, before the bowels are too much weakened and corroded by the stagnant feces; especially if it be given together with castor-oil or fat broth, but no spice. The patient, after taking this medicine, should, if possible, walk about the room; and there are instances in which several ounces, nay, half a pound, and upwards, of pure quicksilver, have been swallowed with the happiest effects. But, in the latter stages of obstinate and violent colics, when inflammation and gangrene have already taken place in the bowels, its specific gravity would infallibly rend the intestines, and accelerate the fatal crisis.—On the whole, we think, preparations of mercury are at present too often employed in medicine, under a great variety of forms, both inter-
