Though mercurials are found to be salutary in sundry cutaneous defedations, and impurities of the blood and juices vulgarly called scorbutic; they are always pernicious in the true scurvy, and dangerous in constitutions inclining to this disease, where the humours are acrimonious, and colliquated, and disposed to a putrescent date. In such circumstances, mercurial medicines are apt to operate with violence: small doses have occasioned high and lading saliva-tions. The removal of these accidents is to be attempted by glysters, purgatives, diaphoretics, or such other means, confident with the patient's strength and the particular symptoms, as may procure a speedy revulsion from the salival ducts.

A long continued use of mercury is in no case free from danger, as it manifestly colli-quates the whole mass of blood, and tends to weaken the nerves, so as to bring on tremors and paralyses. The miners, and those who are exposed to the fumes of mercury in extracting it from the ore, are said to be almost always, sooner or later, seized with these kinds of complaints; to become generally in a few years paralytic, and at last to die hectic.

Mercurials are destructive to infects, perhaps of every kind. They are sometimes given internally against worms; and sometimes applied externally, in unguents, for destroying cutaneous animalcula. The itch, now reckoned an animalcular disease, is sometimes cured by mercurial unguents; which, nevertheless, cannot be depended on for this effect, unless in slight cases; as their antipsoric efficacy seems to reach no farther than those parts of the skin to which they are applied, and as they cannot with safety be applied freely, to any great extent of the body, particularly of the trunk.

Mercury has been of late recommended as an effectual antidote against the poison of the mad dog. Several cases are related, by Dr. James, Default, and Du Choifel, both of brutes and human subjects, bitten by mad dogs, being preserved from the usual consequences of this bite, by mercurial unctions, and mercurials taken internally. There are some instances given also of a cure being obtained, by the same means, after symptoms of madness had appeared (a).

This fluid dissolves, by the assitance of trituration or heat, most metallic bodies; retaining its own natural colour, but having its con-sistence increased in proportion to the quantity of the metal: iron is the only one of the common metals, to which it will not easily adhere(b). Bismuth unites with it more intimately (a) than any other metallic body, and remarkably promotes the union of lead with it: mercury, impregnated with a little bismuth, was found to dissolve considerable masses of lead, in a heat no greater than that of the human body. cases sometimes happen, in which the surgeon may probably avail himself of this property.

(a) James, treatise on canine madness* (b) The other metallic bodies, with which it cannot be united by the usual methods, are regulus of arsenic, and two lately discovered metals called nickel and regulus of cobelt. See Neumann's chemical works, p. 152, etc.

From mod of the fluid amalgams, or mixtures of mercury with metals, great part of the quicksilver may be separated by pressure through leather; but bismuth, and mixtures of bismuth with lead, are so intimately dissolved, as to pass, in considerable quantity, through the leather with it; and hence, with these metals, it has been frequently adulterated. This abuse may be discovered, by the mercury contracting a dull coloured skin upon the surface, or staining paper blackish; by its not running freely into round globules, but forming tears or vermicular striae; by its leaving, upon evaporating a little of it, a powdery matter or a coloured spot on the bottom of the vessel; and by its producing a turbid milkiness during its dissolu-tion in aqua fortis.

Quicksilver is commonly purified from these and other like admixtures, by distilling it in a glass or rather iron retort, or in an iron pot, with a head made of one piece, the vessel commonly used for this purpose by the refiners, and afterwards washing it with vinegar, or with common salt and water. The chemists, suspecting that some metallic bodies (a) may be carried up by the mercury in distillation, recommend certain additions, particularly sulphur; which, from its rendering the mercury itself less disposed to arise, may be presumed to have this effect in a greater degree on the metals that are naturally not volatile: they sub-lime the mercury and sulphur together into cinnabar, which fee in the sequel of this article, and adding to this compound some iron filings to absorb the sulphur, distil off the mercury supposed now to be completely pure. Mr. Malouin recommends uniting the quicksilver with crude antimony instead of sulphur, by leisurely pouring the mercury heated into an equal quantity of antimony made fluid by fire, and then separating the mercury, as from cinnabar, by distillation with iron: the antimony, he says, by virtue of its reguline parts, detains the other metallic bodies more effectually than sulphur can do, and the mercury is thus brought to a state of purity even greater than that of the animated mercuries of the alchemists; for the processes, by which they imagined it to be animated or exalted in its powers, appear to have done no more than to purify it to a certain degree. He has not, however, communicated the particular facts on which this assertion is built; or given any experimental proofs of the greater purity of mercury distilled from antimony, than of such as has been revived from factitious cinnabar, or even of such as has been carefully distilled without addition. The London college now direct the distillation of quicksilver with iron filings alone.

(a) Though part of the bismuth separates spontaneously from the mercury, it does not follow, as some have concluded, that the union is imperfect, or superficial, but that the mercury can retain only a certain quantity of bismuth; and a certain quantity I have found it to retain after long continued agitation.

(a) Boyle, Of volatility and fixedness, Abr. i. 377.