Zinc is a semi-metal of a bluish cast, brighter than lead, and so far malleable as not to be broken by a hammer, though it cannot be much extended. When broken by bending, it appears to consist of cubical grains. If it be heated nearly to melting, it will be sufficiently brittle to be pulverized. It melts long before ignition, and when it is red hot, it burns with a dazzling white flame, and is calcined with such rapidity, that its calx flies up in the form of white flowers, called _flowers of zinc_, or _philosophical wool_. In a stronger heat they become a clear yellow glass. Heated in close vessels, this metal rises without decomposition, being the most volatile of all the metals except the regulus of _arsenic_. Zinc dissolved in diluted vitriolic acid, yields much inflammable air, and has a residuum, which appears to be plumbago, and the liquor forms crystals, called _white copperas_. This metals also yields inflammable air when dissolved in the marine acid. Dissolved in the nitrous acid, it yields dephlogisticated nitrous air, with very little proper nitrous air. The ore of zinc, called _calamine_, is generally of a white colour; and the chief use of it is to unite it with copper, with which it makes brass and other gold-coloured mixtures of metals. The calx and the salts of this metal are occasionally used in medicine. LECTURE XXVIII. _Of Antimony._ The regulus of antimony is of a silvery white colour, of a scaly texture, very brittle, and melts soon after ignition. By continuance of heat it calcines in white fumes, called _argentine flowers of antimony_, which melt into a hyacinthine glass. In close vessels it rises without decomposition. Its calx is soluble in water, like that of arsenic. This metal tarnishes, but does not properly rust, by exposure to the air. This metal is soluble in aqua regia. It detonates with nitre, and what remains of equal parts of nitre and regulus of antimony after detonation, in a hot crucible, is called _diaphoretic antimony_. The water used in this preparation contains a portion of the calx suspended by the alkali, and being precipitated by an acid, is called _ceruse of antimony_. When regulus of antimony is pulverized and mixed with twice its weight of corrosive sublimate (which is attended with heat) and then distilled with a gentle fire, a thick fluid comes over, which is congealed in the receiver, or in the neck of the retort, and is called _butter of antimony_. The residuum consists of revived mercury, with some regulus and calx of antimony. When this butter of antimony is thrown into pure water, there is a white precipitate, called _powder of algaroth_, a violent emetic. Nitrous acid dissolves the butter of antimony; and when an equal weight of nitrous acid has been three times distilled to dryness from butter of antimony, the residuum, after ignition, is called _bezoar mineral_, and seems to be little more than a calx of the metal.