Zinc
a bluish-white lustrous metal, having a crystalline lamellar structure, moderate hardness, somewhat low melting-point. To obtain it pure, commercial zinc, or spelter, as it is termed, is dissolved in pure dilute sulphuric acid; a cement of sulphuretted hydrogen is then passed through it, and it is filtered from any precipitate formed.
The solution is then boiled to expel any sulphuretted hydrogen that may remain in it, and the zinc is precipitated in the form of carbonate by pure carbonate of soda. The carbonate is then ignited to form it into oxide of zinc, which is distilled in a porcelain retort, with charcoal prepared from loaf-sugar. Zinc is brittle at ordinary temperatures, but is possessed of considerable malleability and ductility at a temperature of between 200° and 300°, and may be wrought and rolled with ease. A little above this is becomes brittle again, and may be pulverized in a mortar. It fuses at 773° and at a bright red heat it may be volatilized. If its vapor is exposed to the air, it burns with great splendor, becoming converted into oxide, which ZINC the University of Göttingen he studied is deposited in loose flocculi. At the ordinary temperature it is not acted on by the air, but when exposed to moist air or oxygen, it becomes covered with a tenacious gray coating of hydrated oxide, which impedes the further oxidation of the metal beneath. In this respect zinc rust differs from iron rust, which seems to accelerate the oxidation of the adjacent metal. By the conjoint action of oxygen and carbonic acid, zinc roofing becomes converted into a mixed oxide and carbonate. When melted in the air, the oxide is formed much more rapidly. The metal is readily dissolved by the mineral and vegetable acids.
Boiling solutions of potash also act on zinc, hydrogen being liberated, and oxide of zinc remaining remaining dissolved in the alkaline solution. The difficultly oxidizable nature of zinc, its cheapness, the ease with which it is extracted from its ores, and the ready way in which it may be worked, are bringing it daily more and more into use. Neither the vapor nor its oxide is poisonous.
It is of the greatest use in the laboratory for the precipitation of certain metals and for the formation of hydrogen. For voltaic purposes it is indispensable, and its principal incipal alloy, brass, is too well known to need description.
It forms alloys with iron and several other metals. The so-called galvanic iron is iron covered with a protective coating of zinc. It also enters the composition of German silver. The origin of the term zinc is lost in obscurity; it was first employed by Basil Valentine, but the great Paracelsus was the first to associate the word with a metal possessing the characters of zinc. It hardly seems probable that zinc was known to the ancients. An obscure passage in Strabo seems to show that a certain stone was found to drop false silver when melted, but there is little to show that this false silver was zinc. It is possible, however, that its alloys were known to the later Romans, for numerous coins have been found containing copper and zinc nearly in the proper proportions to form brass. It was not till the beginning of the 18th century that zinc was commercially extracted from its ores in Europe. Before this, however, it was imported by the Portuguese and others from the East Indies and China, under the name of tutenag and spelter. It seems first to have been made in England by Mr. Champion, of Bristol, about the year 1743. Long before zinc was known as a metal, brass was made in large quantities by heating metallic copper imbedded in a mixture of calcined calamine and carbonaceous mat-.
ZINC ter. This was effected in large crucibles, which were exposed to a long-continued heat in furnaces constructed for the purpose. The zinc immediately on its from the course united with the copper without giving any notice of its presence. The only use to which zinc was applied for many years after its discovery was for mixing with copper to form brass; and it was comparatively of late years that the fact of its becoming ductile and malleable when heated was made known.
A patent was granted to the discoverers of this property, Sylvester and Hobson, in 1805, since which period the zinc manufacture has made steady progress.
Zinc has a considerable power of dissolving iron; in consequence of which the iron pots in which it is melted soon become corroded and unfit for use. Its specific gravity varies, according to the closeness of texture of the sample, from 7.03 to 7.2, or even 7.3. Zinc is abundantly distributed in the form of various ores throughout the whole world. Its principal ores are: Red zinc ore, which is found and worked in New Jersey. It consists of oxide of zinc, colored with binoxide of manganese. Carbonate of zinc, or calamine, found extensively in the Devonian and Carboniferous formations of most countries, especially near Lancaster, Columbia co., Pa., where mines were opened in 1853. Hydrated silicate of zinc, which is worked extensively in the United States. Sulphide of zinc, blende, or black jack, which is met with in large quantities in various parts of England and Europe. In the extraction of zinc from its ores, the blende or calamine is first crushed between rollers and roasted. In the case of the blende this is a tedious process, and requires great care. The result in either case is oxide of zinc, which is mixed with half its weight of powdered coke or anthracite, and introduced into crucibles of peculiar constructon. A circular furnace is employed, within which the crucibles are ranged. In the bottom of each crucible is an opening, to which a short iron pipe is attached, passing through the bottom of the furnace. To the end of this is affixed a removable tube communicating with a sheet-iron vessel. The hole in the bottom of the crucible having been partially plugged with coke, a charge of ore and coal is introduced, and the op of the crucible luted down. The tube connected with the iron vessel is lowered so as to leave the crucible tube open, and the heat is raised. So soon as the flame at the mouth of the short iron tube begins to turn from white to blue, connection is made with the tube ZINC leading to the iron pan, and the zinc gradually distils downward, pa partly in powder and partly in stalactitic masses.
The crude metal is remelted, skimmed, and cast into ingots. Silesia and Belgium retorts are used instead of crucibles, or per ascensum instead of per descensum. Zinc is often known in commerce as spelter, the derivation of which term is unknown. The equivalent of zinc, as determined by Erdmann, is 52.53.
Zinc only forms one oxide ZnO, which occurs in nature as red zinc ore. The anhydrous oxide is formed when zinc is burnt in air, and has been occasionally found in four and six-sided prisms in the flues of zinc furnaces. It is best prepared in the laboratory by calcining the precipitate produced by mixing solutions of sesquicarbonate of ammonia and sulphate of zinc. On the large scale, when it is required as a pigment, it is made by distilling zinc in clay retorts, passing into chambers through which a current of air is maintained.
The volatilized metal burns at the high temperature to which it is exposed, and the oxide is deposited in the condensing chambers. As a pigment, it has not met with great success, as it does not wear so well as white lead, from its lesser specific gravity. In situations where it is exposed to sulphurous fumes, it stands perfectly; and being harmless in its nature, it is not open to the objections raised against its poisonous congener. Oxide of zinc forms a light white powder, which becomes yellow when heated, regaining its whiteness when it cools. It is a permanent oxide, even at the greatest heat. When exposed to the air, it becomes converted into a carbonate. It dissolves readily in acids, and its salts have the same form as those of magnesia and oxide of iron, with which it is isomorphous. Its salts, though neutral in composition, have an acid reaction. It is not easily dissolved in solutions of potash and soda, but if fused with them in a silver crucible, it forms compounds soluble in water in which the oxide of zinc appears to play the part of an acid. The hydrated oxide is formed by adding a solution of potash to the sulphate of zinc. It is readily soluble in excess of alkaline solution. In medicine, oxide of zinc is used in ointments as an astringent and desiccant, and by itself as a tonic, especially in cases of nervous debility brought on by drinking. Zinc is said to be a binoxide, but it requires confirmation. Nitrate of zinc is prepared by dissolving zinc in dilute nitric acid. It forms deliquescent four-sided prisms, 1 ZINC ZION soluble in water and alcohol. Sulphate found native contaminated with a large of zinc, or white vitriol, is manufactured on a large scale by roasting native sulphide of zinc (blende), extracting the mass with water, and evaporating to the crystallizing point. It is gen generally sent into commerce in white fused masses.
Generally speaking, it contains six atoms prisms. It is used in medicine as an pounds containing less have been formed.
It crystallizes ordinarily in four-sided prisms. It is used in medicine as an emetic, and very largely by calico printers. It is soluble in 2½ parts of water, sulphates are said to exist. It combines directly with ammonia, forming a defisulphates are said to exist. It combines nite compound. It also forms double sulnite compound. It also forms double sulphates with those of potassa, ammonia, magnesia, and protoxide of iron. Car- bonate of zinc, or calamine, occurs in magnesia, and protoxide of iron. nature in large amorphous masses, and occasionally in crystals of the same form as those of carbonate of lime. It is the chief ore of zinc, and is employed in its impure state in medicine as an exsiccant, and in healing cerates. The anhydrous carbonate may be prepared in the laboratory by placing a tube containing carbonate of soda in a strong tube containing sulphate of zinc, sealing the outer tube hermetically, heating it to 320° F., and inverting it so that the solution may mix; crystalline grains of the anhydrous carbonate are gradually deposited. No neutral carbonate of zinc can be obtained from its salts by double decomposition.
Chloride of zinc is prepared by dissolving granulated zine in hydrochloric acid, and evaporating, when it is obtained in a semi-solid hydrated mass, known as butter of zinc. If this be further heated, It is deliquescent, fuses ea easily, and may be distilled. It is remarkably soluble in water, and its strong affinity for that substance renders it of great use as a desiccating agent in organic research.
In solution it forms Burnett's disinfect substance renders it of great use as a desiccating agent in organic research. when applied to the skin, and is used in surgery for that purpose. It fuses above 700° F., but does not decompose unless more strongly heated; hence a bath of it is sometimes used for maintaining objects at a high temperature. Its solution more strongly heated; hence a bath of it is sometimes used for maintaining ob- It forms double salts with the chlorides of the alkaline metals. Its solution is also much used in soldering zinc, iron, and copper. Its solution is also much used for preserving objects for dissection, as it does not corrode the instruments in the same way as corrosive subalso much used in soldering zinc, iron, exist. Sulphide of zinc, or blende, is number of the other metals. It may be prepared by the direct combination of its an alkaline sulphide to a solution of elements. The hydrated sulphide is obsome zinc salt. There are several oxytained as a white precipitate, by adding or electric calamine, is found native in sulphides of zinc. The trisilicate of zinc, was 123,886 short tons, the largest on record. Illinois, Indiana, Kansas, and Missouri were the chief producing States. several parts of the world. Heat de- United States in the calendar year 1900 in combating nervous disorders.
The production of spelter in the United States in the calendar year 1900 was 123,886 short tons, the largest on record. Illinois, Indiana, Kansas, and came the exporter of both metal and ore Missouri were the chief producing States.
For the first time the United States bein that year. The production of primary zinc in the United States in 1919 was 452,272 second, and Kansas third. In 1919 the United States produced practically all homa ranked first in the production of zinc, with 121,988 tons; Illinois was second, and Kansas third. In 1919 the United States produced practically all the zinc smelted. Zinc imports in year amounted to 48,649 tons of ore, 17,009 tons of zinc content, with a total value of $529,660. The exports of zinc in 1919 were valued at $50,530,132. in that alliance Amomales. Aromatic herbs, order of endogens, the typical one of the with a creeping, often jointed rhizome.
Stem simple, formed of the cohering very numerous parallel veins diverge at an acute angle and proceed to the mar- gin; flowers generally in pairs, and lying bases of the leaves; leaves simple sheathan acute angle and proceed to the margin; flowers generally in pairs, and lying very numerous parallel veins diverge at among spathaceous bracts; an bracts; calyx supetubular, irregular, with six segments in two whorls, the inner, morphologically viewed, being transformed sterile statwo whorls, the inner, morphologically rior, short, tubular, three-lobed; corolla, them abortive; filament of the former viewed, being transformed sterile stanot petaloid; anther, two-celled; style mens, untransformed stamens three, two more or less perfectly three-celled, the placenta in the axis; fruit, usually a filiform; stigma, dilated, hollow; ovary, capsule, three, or sometimes one celled; they were formerly seeds, many. Closely akin to Marananther, and in the possession of a vitaceæ, with which the combined, but differ in their two-celled countries. Genera, 29; species, 247. anther, and in the possession of a vi- tellus round the embryo. Natives of the East Indies and some other tropical