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water: a piece of iron or zinc throws down themetal in the ftate of black oxyd, which, whendried at a low temperature, has been obfervedby Thenard, to exhibit the properties of apyrophorus, inflaming fpontaneoufly by expo-lure to the air.

The Fluoric and Boracic acids have no aftionon reguline antimony; but when digefted onthe grey oxyd of this metal they combine withit, and form cryllallizable falts, the propertiesof which have not yet been examined.

The arfenic acid, when digefted upon regulineantimony, produces two compound fubftances ;one remains infoluble at the bottom of the fluid,and confifts of the oxyds of arfenic and anti-mony, being an arfenite of antimony ; the otheris diffolved in the fupernatant liquor, and iseither a true arfeniat of antimony, or, perhaps,differs from the infoluble refidue only, in con-taining a fmaller proportion of antimony. Theformer of thefe falts is foluble in muriatic acid,from which it is precipitable by water. h Ifdry arfenic acid and regulus of antimony arediftilled together, as foon as the mafs becomesfluid, an inflammation takes place, regulus ofarfenic fublimes into the neck of the retort,and what remains behind is a mixture of theoxyds of arfenic and antimony. Arfenic acidhas no effedt on the fublimed muriat of anti-mony, but the neutral arfeniats decompofe itwithout difficulty, throwing down an arfeniat of- antimony.

The effe£t of the vegetable acids uponmetallic antimony is fcarcely perceptible : thofehowever of its oxyds which are not faturatcdwith oxygen are foluble without much difficulty.Tartareous acid, by long digeftion, may be madeto take up about one-third or one-fourth of itsown weight of antimonial oxyd : the folution,when evaporated and cooled down to the propertemperature, depofits a few cryftalline grains oftartrite of antimony ; by far the greater portion,however, is of a gelatinous confiftence, and hasnot been much examined. Tartrite of potafhwill alfo take up nearly as much antimonialcxyd as tartareous acid does; the liquor be-comes {lightly alkaline, and depofits, by evapo-ration, a number of cryftalline grains. Butthe combination of cream of tartar, or acidu-lous tartrite of potafh, with antimony, com-mon’y known by the name of emetic tartar, isthat which, from its importance in medicine,has been the moll accurately examined.

A folution of tartareous acidulum takes up at' a boiling temperature a confiderable proportion

of oxyd of antimony, and by evaporation andcooling depofits elongated octahedral cryftals ofemetic tartar. As, however, the materials ofthis fait are hardly ever perfectly pure, and asthe method of preparing it is by no means uni-form; the efficacy of this important medicineis liable to confiderable variation, as well asthe analyfes that have been publifhed of itscomponent parts. Common cream of tartar is-always contaminated with a fmall quantity oftartrite of lime, and the glafs of antimony whichis the antimonial oxyd generally made ufe of,contains, befides, a variable proportion of ful-phur, as well as fome filex, from the earthencrucibles in which it is made, and which are, infome degree, corroded by it. In order, there-fore, to prepare a pure and uniform emetictartar in the moll economical manner, the fol-lowing directions muff be carefully attended to.

Take 12 ounces of glafs of antimony, andreduce it to a very fine powder, to which add aboiling hot folution of 16 ounces of cream oftartar in 14 quarts of rain water; put the wholein a proper veffel on a digelting find bath, andkeep ftirring it with a {tick for the fpace of halfan hour ; the liquor will foon be covered witha brownifh froth, and fome fulphuretted hydro-gen gas will be given out; when the difengage-ment of this gas begins to ceafe, make thefolution boil gently for about ten minutes, afterwhich, remove the veffel from the fire, andwhen the liquor is become clear, transfer it intoa clean evaporating difh, and, by a very gentleheat, reduce it almoft to drynefs, in order toprecipitate the filex, which would otherwifeconvert the whole to a gelatinous mafs, andprevent, in a confiderable degree, the after crys-tallization : when the fait is nearly dry, add hotwater as long as any thing continues to be dif-folved ; then {train the liquor, which will be ofa bright wine colour, and evaporate it to apellicle : by Handing for a night, a number ofoCtahedral and tetrahedral cryftals will bedepofited, which are pure antimoniated tartar,and by further evaporation and cooling, a frefhquantity may be obtained, being altogetherfomewhat more than the tartar made ufe of.The tafte of this triple fait is {lightly harfh andmetallic: it reddens vegetable blues, as doalmolt all the other metallic falts. When expofedto the air it lofes its tranfparency, and becomescovered over with a white powder. It requiresfor its folution about forty times its weight ofboiling water and nearly twice as much as thecommon temperature. Sulphuric acid jtrecipi-

*■ Schecks EiT. p. 183.