The calces of mercury next claim our attention. Dr. Priestley informed us, that mercury triturated with water might be changed into a black powder; but the fact was published by Homberg in the Memoirs of the Academy of Sciences for 1700. This preparation, if it may be so called, has been highly celebrated under the name of AEthiops mineralis per se; more properly, mercurius oxidatus niger: but its chief use has been to unite with the vegetable acid in making Keyser's pills; and, triturated with axunge, to prepare extemporaneously the mercurial ointment. The pulvis vigonis is only the mercurius calcinatus; and Schroeder's praecipitatus dulcis is prepared by calcining quicksilver with the red precipitate which has been deflagrated with spirit of wine. The red precipitate itself is the preparation which distinguishes Girtanner's un-gncntum rubrum; and forms, with burnt alum, eu-phorbium, dry leaves of savine, the roots of iris, and aristolochia rotunda, the pulvis catheriticus, for carious bones, of Schrocder. With minium and ceruse it forms the unguentum piacentinum of the hospital at Padua; and with tutty, nitre, and camphor, the celebrated ointment of Mursinna for restoring the transparency of the cornea. The praecipitatum nobile of An-gclus Sala is only the red precipitate with a small portion of the muriatic acid; since it is prepared by calcining a solution of a calx of mercury in aqua regia. It is highly commended by its author in a malignant itch. The arcanum corallinum and mercurius corallinus are preparations of Crollius, described in Lewis's Dispensatory; and the laudanum minerale of Hartmann is the former, first digested with vinegar, which is again separated by distillation, and afterwards with spirit of wine. It is supposed to be a gentle laxative, and then an anodyne and sudorific. The rosa vita mineralis is the red precipitate, digested four times with spirit of wine. The panacea mercurialis rubra, praeci-pitatus diaphoreticus excellens, turbith minerale rubrum Zwelferi; pulvis Principis, and mercurius antivenereus of Hartmann, are similar preparations, in which the red precipitate is rendered milder by digesting it with spirit of wine. In the two last it is previously elutriated with water, to which an alkali is added in some of the latter washings. Various similar preparations of mercury are found in chemical authors; but we shall only notice Hahnemann's mercurius solubilus, which, in his Chemical Annals for 1790, he mentions with the warmest commendations, as producing no inconvenience in the stomach or bowels, being soluble in vinegar and in the animal fluids, and easily absorbed when applied externally. It seems to be a calx of mercury, precipitated from a solution of the metal in pure aqua fortis by the caustic spirit of sal ammoniac. This preparation has been also called turbith nigrum.

The greater number of the calces of mercury have some remaining saline matter, and this is particularly the case with the mercurius praepitatus albus, the calx hydrargyri alba, which we again mention to introduce its numerous singular synonims. These are mercurius cosmeticus; lac mercuriale; calcinatum majus poterii; panacea mercurii albi; catharlicum mercuriale; and, when washed, manna mercurii. It is chiefly used on the continent as an external application, and is highly commendedin the itch. Authors of credit have, however, we perceive, given it internally, and speak highly in its favour: when sublimed, dissolved in water, and again sublimed, it is styled aquila celestis.

A modern preparation of mercury similar to Hahnemann's mercurius solubilis, is the hydrargyrum nitra-tum cinereum of Swediaur; pulvis mercurii cinereus of Girtanner; called, for a reason that we cannot develop, mercurius cinereus of Black. It is mercury, precipitated from its solution in aqua fortis by a mild volatile alkali, and is of a lighter colour than the turbith nigrum.

The praeipitatus luteus of Hartmann is not greatly different, as it is precipitated by a mild fixed alkali, and acquires its yellow colour by washing. The praecipita-tus luteus diaphoreticus of the same author is a solution of the corrosive sublimate, precipitated by the. same alkali, and carefully washed. Mercurius dejecto-rius, or the flores argenti, is the praecipitatus luteus of Hartmann, digested in the acetous acid, and then washed. The praecipitatus correctus of Schrocder is prepared by dissolving the white precipitate in vinegar, and again separating it by a fixed vegetable alkali.

The improved chemistry has introduced some new preparations of rnercury. The first that occurs to us is the mercurius phosphoratus, sal phosphoricum mercuriale, and phosphoras mercurii, with some similar appellations. It is a white salt, unchanged in the air, and scarcely soluble in water, prepared by precipitating mercury from its solution in aqua fortis by the phosphoric acid. This preparation is slightly mentioned by Girtanner and Swediaur, but chiefly introduced by a French quack, M. Mittie, followed by a German, J. Fr. Schmidt. It is highly praised in the worst stages of syphilis, particularly in the most inveterate kinds when the bones are affected, and is given with aromatics to prevent its exciting nausea, in the dose of half a grain, or a grain. We own that these assertions are to us suspicious: we know that the use of phosphorus is dangerous, and have no reason, from the facts adduced by the admirers of the phosphorated mercury, to suppose that this is a safe or manageable preparation. We can add, that it is by no means new; for we observe in Angelus Sala a preparation styled pulvis rosae vita, copied by Hartmann, who calls it mercurius incarnatus praecipitatus, in which the nitrated mercury is precipitated by urine. We know that this fluid contains the muriated ammonia and the oxalic acid, which may alter in some measure the nature of the precipitate. It is certainly milder, since these authors admit that it may be given from six to ten grains, and is then a cathartic.