LECTURE XXVII.

_Of Nickel._

Nickel is a semi-metal of a reddish cast, of great hardness, and always magnetical; on which account it is supposed to contain iron, though chemists have not yet been able to separate them.

The purest nickel was so infusible as not to run into a ma.s.s in the strongest heat of a smith's forge; but then it was in some degree malleable.

Concentrated acid of vitriol only corrodes nickel. Alkalies precipitate it from its solution in the nitrous acid, and dissolve the precipitate.

It readily unites with sulphur.

Nickel is found either native or mineralized with several other metals, especially with copper, when it is called _kupfer nickel_, or _false copper_, being of a reddish or copper colour.

This semi-metal has not yet been applied to any use.

_Of a.r.s.enic._

What is commonly called _a.r.s.enic_ is the calx of a semi-metal called the _regulus of a.r.s.enic_. It is a white and brittle substance, expelled from the ores of several metals by heat. It is then refined by a second sublimation, and melted into the ma.s.ses in which it is commonly sold.

This calx is soluble in about eighty times its weight of cold water, or in fifteen times its weight of boiling water. It acts in many respects like an acid, as it decomposes nitre by distillation, when the nitrous acid flies off, and the _a.r.s.enical salt of Macquer_ remains behind.

When the calx of a.r.s.enic is distilled with sulphur, the vitriolic acid flies off, and a substance of a yellow colour, called _orpiment_, is produced. This appears to consist of sulphur and the regulus of a.r.s.enic; part of the sulphur receiving pure air from the calx, to which it communicates phlogiston; and thus the sulphur becomes converted into vitriolic acid, while the a.r.s.enical calx is reduced, and combines with the rest of the sulphur.

The combination of sulphur and a.r.s.enic, by melting them together, is of a red colour, known by the name of _realgal_, or _realgar_. It is less volatile than orpiment.

The solution of fixed alkali dissolves the calx of a.r.s.enic, and by means of heat a brown tenacious ma.s.s is produced, and having also a disagreeable smell, it is called _liver of a.r.s.enic_.

The regulus of a.r.s.enic is of a yellow colour, subject to tarnish or grow black, by exposure to the air, very brittle, and of a laminated texture.

In close vessels it wholly sublimes, but burns with a small flame in pure air.

Vitriolic acid has little action upon this semi-metal, except when hot; but the nitrous acid acts readily upon it, and likewise dissolves the calx, as does boiling marine acid, though it affects it very little when cold.

Most of the metals unite with the regulus of a.r.s.enic.

Dephlogisticated marine acid converts the calx of a.r.s.enic into _a.r.s.enical acid_ by giving it pure air.

The acid of a.r.s.enic acts more or less upon all metals, but the phenomena do not appear to be of much importance.

The calx of acid is used in a variety of the arts, especially in the manufactory of gla.s.s. Orpiment and realgar are used as pigments. Some attempts have been made to introduce it into medicine, but being dangerous, the experiments should be made with caution.

_Of Cobalt._

Cobalt is a semi-metal of a grey or steel colour, of a close-grained fracture, more difficult of fusion than copper, not easily calcined. It soon tarnishes in the air, but water has no effect upon it.

Cobalt, dissolved in _aqua regia_, makes an excellent sympathetic ink, appearing green when held to the fire, and disappearing when cold, unless it has been heated too much, when it burns the paper.

The calx of cobalt is of a deep blue colour, which, when fused, makes the blue gla.s.s called _smalt_. The ore of cobalt, called _zaffre_, is found in several parts of Europe, but chiefly in Saxony. As it is commonly sold, it contains twice or thrice its weight of powder of flints. The smalt is usually composed of one part of calcined cobalt, fused with two parts of powder of flint and one of pot-ash.

The chief use of cobalt is for making smalt; but the powder and the blue-stone used by laundresses is a preparation made by the Dutch of a coa.r.s.e kind of smalt.

_Of Zinc._

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 gla.s.s. Heated in close vessels, this metal rises without decomposition, being the most volatile of all the metals except the regulus of _a.r.s.enic_.

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 bra.s.s 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 gla.s.s. In close vessels it rises without decomposition. Its calx is soluble in water, like that of a.r.s.enic. 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 _diaph.o.r.etic 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 _b.u.t.ter of antimony_. The residuum consists of revived mercury, with some regulus and calx of antimony. When this b.u.t.ter of antimony is thrown into pure water, there is a white precipitate, called _powder of algaroth_, a violent emetic. Nitrous acid dissolves the b.u.t.ter of antimony; and when an equal weight of nitrous acid has been three times distilled to dryness from b.u.t.ter of antimony, the residuum, after ignition, is called _bezoar mineral_, and seems to be little more than a calx of the metal.

Crude antimony, which has been much used in the experiments of alchemists, is a combination of sulphur and regulus of antimony. Heat melts it, and finally converts it into gla.s.s, of a dark red colour, called _liver of antimony_. If antimony be melted or boiled with a fixed alkali, a precipitate is made by cooling, called _kermes mineral_, formerly used in medicine. The antimonial preparations that are now most in use are _antimonial wine_ and _tartar emetic_. The wine is made by infusing pulverized gla.s.s of antimony in Spanish wine some days, and filtering the clear fluid through paper. The emetic tartar, or antimonial tartar, is a saline substance, composed of acid of tartar, vegetable alkali, and antimony partially calcined. The preparation may be seen in the Dispensaries.

The regulus of antimony is used in the form of pills, which purge more or less in proportion to the acid they meet with; and as they undergo little or no change in pa.s.sing through the body, they are called _perpetual pills_.

_Of Manganese._

Manganese is a hard, black mineral, very ponderous, and the regulus of it is a semi-metal of a dull white colour when broken, but soon grows dark by exposure to the air. It is hard and brittle, though not pulverizable, rough in its fracture, and of very difficult fusion. Its calces are white when imperfect, but black, or dark green, when perfect.

The white calx is soluble in acids. When broken in pieces, it falls into powder by a spontaneous calcination, and this powder is magnetical, though the ma.s.s was not possessed of that property. The black calx of manganese is altogether insoluble in acids. It contains much dephlogisticated air.

The calx of manganese is used in making gla.s.s; the gla.s.s destroying the colour of that of the other materials, and thereby making the whole ma.s.s transparent.

This semi-metal mixes with most of the metals in fusion, but not with mercury.

There is another ore of manganese, called _black woad_, which inflames spontaneously when mixed with oil.

_Of Wolfram._

Wolfram is a mineral of a brownish or black colour, found in the tin mines of Cornwall, of a radiated or foliated texture, shining almost like a metal. It contains much of the calx of manganese, and iron; but when the substance is pulverized, these are easily dissolved, and the calx of wolfram is found to be yellow.