Obs. Four shades of this beautiful pigment are met with in the shops, viz. pale yellow or straw colour, yellow, deep yellow, and orange. The former are made by adding a little alum or sulphuric acid to the solution of the chromate before mixing it with the solution of lead; the last, by the addition of a little subacetate of lead (tribasic acetate), or by washing the precipitate with a weak alkaline lye. The darker colour appears to arise from a little ‘dichromate’ being thrown down intimately mixed with the neutral chromate, and the paler shades from a slight excess of acid, or from the presence of water-sulphate of lead, and, occasionally, alumina. The colour is also influenced by the temperature of the solutions at the time of admixture. Anthon has found that, when hot solutions of equal equivalents of acetate of lead (190 parts) and chromate of potash (100 parts, both neutral and in crystals) are mixed, the yellow precipitate, when dried, is anhydrous; but when the mixture is made at ordinary temperatures, the precipitate has a paler yellow, and when dried contains 1 eq., or nearly 5¹⁄₄% of water. (‘Buch. Rept.’) It thus appears that the shades of colour of chrome yellow may be varied, without any foreign addition. In practice, the third formula will be found very satisfactory. See Orange Chrome and Chrome Red.

Dutch Pink. Prep. Take of French berries, 1 lb.; turmeric, ¹⁄₂ lb.; alum, ¹⁄₂ lb.; water, 1¹⁄₂ gall.; boil ¹⁄₂ an hour, strain, evaporate to 2 quarts, adding of whiting, 3 lbs., and dry by a gentle heat. Starch, or white lead, is sometimes employed instead of whiting, to give it a body. Golden yellow. Used as a pigment; but will not glaze like brown pink.

English Pink. Syn. Light pink. As the last, but using 5 lbs. of whiting.

Indian Yellow. See Purree.

King’s Yellow. Factitious tersulphuret of arsenic.

Naples Yellow. Syn. Mineral yellow. Prep. 1. Take of metallic antimony, in powder, 3 lbs.; red lead, 2 lbs.; oxide of zinc, 1 lb.; mix, calcine, well triturate the calx, and fuse it in a covered crucible; the fused mass must be reduced to an impalpable powder by grinding and elutriation.

2. Flake white, 1¹⁄₂ lb.; diaphoretic antimony, ¹⁄₄ lb.; calcined alum, 1 oz.; sal ammoniac, 2 oz.; calcine in a covered crucible with a moderate heat for 3 hours, so that at the end it may be barely red hot. More antimony and sal ammoniac turn it on the gold colour.

3. (Guimel.) Washed diaphoretic antimony, 1 part; pure red lead, 2 parts; grind them to a paste with water, and expose this mixture to a moderate red heat for 4 or 5 hours, as before. Used in oil, porcelain, and enamel painting. Chrome has now nearly superseded it for ordinary purposes.

Patent Yellow. Syn. Cassel Yellow, Montpellier y., Turner’s y. Prep. Take of dry chloride of lead, 28 parts; pure carbonate of lead, 27 parts; grind them together, fuse, and powder.

2. Common salt, 1 part, and litharge, 4 parts, are ground together with water, and digested at a gentle heat for some time, water being added to supply the loss by evaporation; the carbonate of soda formed is then washed out with more water, and the white residuum heated until it acquires a fine yellow colour. Works well in oil. Chiefly used in coach-painting. See Oxychloride of lead.

Weld Yellow. Prepared from a decoction of weld brightened with a little alum, in the same manner as Dutch pink. Used chiefly for paper hangings.

YTTRIUM. Y. The oxide of this metal (yttria), a rare, white earth, was discovered by Gadolin, in 1794, in a mineral from Ytterby, in Sweden, since called gadolinite. Yttrium was obtained by Wöhler in 1828, as a brittle, dark-grey metal, made from the chloride by the action of sodium. Its salts have in general a sweetish taste, and the sulphate and several others an amethystine colour. Its solutions are precipitated by pure alkalies, but alkaline carbonates, especially carbonate of ammonium, dissolve it in the cold. They are distinguished from glucinium salts by the colour of the sulphate by being insoluble in pure alkalies, and by yielding a white precipitate with ferrocyanide of potassium. Yttria may be obtained from gadolinite by a similar process to that by which glucina is extracted from the beryl.

According to Professor Mosander, ordinary yttria is a mixture of the oxides of not less than three metals—yttrium, erbium, and terbium. These metals differ from each other in many important particulars. The first is a powerful base, and the others are said to be weak ones. They are separated with extreme difficulty, and are only interesting in a scientific point of view.

ZAF′FRE. Syn. Saffra, Safflor, Zaffer. Crude oxide of cobalt, obtained by roasting cobalt ore, reduced to an impalpable powder, and then ground with 2 or 3 parts of very pure quartzose or siliceous sand. Used as a blue colour by enamellers and painters on porcelain and glass. Chiefly imported from Saxony. See Smalts.

ZE′′RO. See Thermometer.

ZESTS. See Powders, Sauce, Spice, &c.

ZINC. Zn. Syn. Zink, Spelter; Zincum. (Ph. L., E., & D.), L. This metal was first noticed by Paracelsus, in the 16th century, who called it ‘zinetum,’ but its ores must have been known at a much earlier period, as the ancients were acquainted with the manufacture of brass.

Prep. The zinc of commerce is obtained from the native sulphide (zinc blende), or carbonate (calamine), by roasting those ores, and distilling the calx with carbonaceous matter in a covered earthen crucible, having its bottom connected with an iron tube, which terminates over a vessel of water situated beneath the furnace. The first portion that passes over contains cadmium and arsenic, and is indicated by what is technically called ‘brown blaze,’ but when the metallic vapour begins to burn with a bluish-white flame, or the ‘blue blaze’ commences, the volatilised metal is collected.

The following method, by which several pounds of chemically pure zinc may be obtained in about ¹⁄₄ of an hour, will be found very useful:—Melt the zinc of commerce in a common crucible, and granulate it by throwing it into a tolerably deep vessel of water, taking care that the metal be very hot at the time; dry the metallic grains, and dispose them by layers in a Hessian crucible with ¹⁄₄ of their weight of nitrate of potassium, using the precaution to place a slight excess at the top and at the bottom; cover the crucible, and secure the lid, then apply heat; after the vivid deflagration which occurs is over, remove the crucible from the fire, separate the dross with a tube, and, lastly, run the zinc into an ingot mould. This zinc, tested in Marsh’s apparatus during entire days, has never given any stain, and in solution the most sensitive reagents, such as hydro-sulphocyanic acid, have never indicated the least atom of iron. (‘Journ. de Pharm.’)

Prop. Zinc is a bluish-white metal, having the sp. gr. 6·8 to 7·2; tough (under some circumstances, brittle) when cold, ductile and malleable at from 250° to 300° Fahr.; brittle and easily pulverised at 400°; fuses at 773° (Daniell); at a white heat it boils, and sublimes unchanged in close vessels; heated to whiteness (941° Daniell) in contact with the air, it burns with a brilliant green light, and is converted into oxide. It is very soluble in dilute sulphuric and hydrochloric acid, with the evolution of hydrogen gas. It is little acted on by the air, even when moist. The salts of zinc are colourless.

Pur. Commercial zinc is never pure. Its specific gravity is 6·86. It is soluble in nitric, hydrochloric, and dilute sulphuric acids.

Tests. 1. The solutions of zinc give a gelatinous white precipitate with the alkalies and carbonate of ammonium, which is completely redissolved by an excess of the precipitant.—2. The carbonates of potassium and sodium give a white precipitate of carbonate of zinc. All the above precipitates acquire a lemon-yellow colour when dried and heated, but again become white on cooling.—3. Sulphide of ammonium gives, in neutral solutions, a white precipitate, insoluble in excess of the precipitant, or in solutions of hydrate of potassium or ammonium, but freely soluble in the dilute mineral acids.—4. Sulphuretted hydrogen, in neutral and alkaline solutions, also gives a like white precipitate.—5. Ferrocyanide of potassium gives a gelatinous white precipitate.

Estim., &c.—a. 100 gr. are digested in dilute hydrochloric acid in excess, and the insoluble portion, which is chiefly carbon, dried and weighed.

b. The acidulous solution (see a) is next treated with a current of sulphuretted hydrogen until it smells very strongly of that gas; the whole is then left for some time in a warm situation. The precipitate which subsides consists of the sulphides of arsenic, cadmium, copper, lead, &c., if any of these metals were present in the sample.

c. The filtrate from b, after being boiled, is treated with a little nitric acid, after which it is again boiled, and, when cold, is precipitated with carbonate of barium added in excess; the precipitate (ferric hydrate) is then collected, dried, ignited, and weighed. The weight, in grains, multiplied by ·7, gives the percentage of iron in the sample examined.

d. The filtrate from c is next precipitated with dilute sulphuric acid, and solution of carbonate of sodium is added in excess to the filtered liquid; the whole is then boiled, after which the new precipitate is washed, dried, gently ignited for some time, and then cooled and weighed. The weight, in grains, multiplied by ·80247, gives the percentage of pure zinc in the sample.

Uses, &c.—Zinc is used to form galvanic plates; in fireworks, and in medicine. Of late years it has also been extensively used in the manufacture of vessels of capacity, tubing, sheets for roofing, and other things that require lightness and durability.

Zinc, Amalgamated, which is employed for voltaic batteries, is prepared as follows:—The plates, having been scoured with emery, are immersed for a few seconds in dilute sulphuric acid, then rinsed in clean soft water, and, after the loose water has drained from their surface, dipped into a strong solution of either mercuric nitrate or chloride, or into equal parts of a mixture of saturated solutions of mercuric chloride and acetate of lead; the plates are, lastly, dipped into water, and then rubbed with a soft cloth. Another and simpler method is to rub mercury over the plates while wet with dilute sulphuric acid.

Zinc, Granulated. Syn. Zincum granulatum (B. P.). Fuse commercial zinc in a crucible, pour it in a very thin stream into a bucket of cold water, and afterwards dry the zinc.

Zinc, Ac′etate of. Zn(C₂H₃O₂)₂. Syn. Zinci acetas, L. Prep. 1. (Ph. D.) Acetate of lead, 1 lb., is dissolved in distilled water, 2¹⁄₂ pints, and the solution being placed in a cylindrical jar, sheet zinc, 4 oz., rolled into a coil, is immersed therein; after 24 hours the liquid is decanted, evaporated to 15 oz., and solution of hypochlorite of calcium added drop by drop, until a reddish precipitate ceases to form; the liquid is then filtered, acidulated by the addition of a few drops of acetic acid, reduced by evaporation to 10 fl. oz., and set aside to crystallise; the crystals are dried on bibulous paper set on a porous brick, and then preserved in a well-stopped bottle. More crystals may be obtained from the mother-liquor.

2. (B. P.) Add 2 oz. of carbonate of zinc in successive portions to 3 fl. oz. of acetic acid, previously mixed with 6 fl. oz. of distilled water, in a flask; heat gently, add by degrees 2 fl. oz. of acid, or q. s., till the carbonate is dissolved; boil for a few minutes, filter while hot, and set it aside for two days to crystallise. Decant the mother liquor, evaporate to one half, and again set it aside for two days to crystallise. Place the crystals in a funnel to drain, then spread them on filtering paper on a porous tile; and dry them by exposure to the air at ordinary temperatures.

Prop., &c. Efflorescent, white, hexagonal plates, having a powerful styptic taste; very soluble in water; less soluble in alcohol; decomposed by heat. It is tonic, antispasmodic, and emetic.—Dose, 1 to 2 gr.; as an emetic, 10 to 20 gr.; externally, 2 or 3 gr. to water, 1 fl. oz., as an astringent lotion or injection.

Zinc, Bro′mide of. ZnBr₂. Syn. Zinci bromidum, L. Prepared like the corresponding salt of iron.

Zinc, Car′bonate of. ZnCO₃. Syn. Zinci carbonas purum, Zinci carbonas (B. P., Ph. D.), L. Prep. 1. (Ph. D.) Solution of chloride of zinc (Ph. D.), 1 pint is added, in successive portions, to a solution of crystallised carbonate of sodium of commerce, 2 lbs., dissolved in boiling distilled water, 6 pints, and the whole is boiled until gas ceases to be evolved; the precipitate is then washed, and dried, at first on blotting-paper, and, finally, by a steam or water heat.

2. (B. P.) Dissolve 10¹⁄₂ oz. carbonate of soda with 1 pint of boiling water in a capacious porcelain vessel, and pour into it 10 oz. of sulphate of zinc, also dissolved in 1 pint of water, stirring diligently. Boil for 15 minutes after effervescence has ceased, and let the precipitate subside. Decant the supernatant liquor, pour on the precipitate 3 pints of boiling distilled water, agitating briskly; let the precipitate again subside, and repeat the process of affusion of hot distilled water and subsidence till the washings are no longer precipitated by chloride of barium. Collect the precipitate on calico, let it drain, and dry it with a gentle heat.

Zinc, Chlo′′ride of. ZnCl₂. Syn. Butter of zinc, Muriate of z.†; Zinci chloridum (B. P., Ph. L.), Z. murias†, L. Prep. 1. By heating metallic zinc in chlorine.

2. (Ph. L.) Hydrochloric acid, 1 pint; water, 1 quart; and zinc (in small pieces), 7 oz.; when the effervescence is nearly finished, apply heat until bubbles cease to be evolved; decant the clear, and evaporate to dryness; fuse the resulting mass in a lightly covered crucible, by a red heat, pour it out on a flat smooth stone, and, when cold, break it into small pieces, or cast it into rods in iron moulds, and preserve it in a well-stoppered bottle.

3. (B. P.) Put 16 oz. of granulated zinc into a porcelain basin, add by degrees 44 fl. oz. of hydrochloric acid previously mixed with 1 pint of distilled water, and aid the action by gently warming it on a sand-bath, until gas is no longer evolved. Boil for half an hour, supplying the water lost by evaporation, and allow it to stand on the cool part of the sand-bath for 24 hours, stirring frequently. Filter the product into a gallon bottle, and pour in solution of chlorine q. s. by degrees, with frequent agitation, until the fluid acquires a permanent odour of chlorine. Add ¹⁄₂ oz. or a sufficient quantity of carbonate of zinc, in small quantities at a time, and with renewed agitation, until a brown sediment appears. Filter through paper into a porcelain basin, and evaporate until a portion of the liquid, withdrawn on the end of a glass rod and cooled, forms an opaque white solid. Pour it out now into proper moulds, and when the salt has solidified, but before it has cooled, place it in closely-stoppered bottles.

4. (In SOLUTION).—a. (Liquor zinci chloridi—Ph. D.) Hydrochloric acid and water, of each 2¹⁄₂ pints; sheet zinc, 1 lb.; dissolve, filter through calico, add of hypochlorite of calcium, 1 fl. oz., and evaporate, by boiling, to a pint; when cold, pour it into a bottle, add of prepared chalk, 1 oz., and water, q. s. to make the whole measure 1 quart; agitate occasionally for 24 hours, decant or filter, and preserve the liquid in a stoppered bottle. Sp. gr. 1·593. See Solutions.

b. (E. Parrish.) Granulated zinc, 4 lbs.; hydrochloric acid, 4 lbs., or q. s.; water, 9 quarts; dissolve, avoiding excess of acid. The solution contains 1 in 12 of chloride of zinc. Recommended as of the proper strength for a disinfectant.

Prop., &c. When pure, a colourless, amorphous mass or crystals; generally a whitish-gray, semi-transparent mass, having the consistence of wax; fusible; volatile at strong heat, condensing in acicular crystals; freely soluble in alcohol, ether, and water; highly deliquescent; coagulates albumen and gelatin, and corrodes animal substances. The solution possesses the same properties in a minor degree.

Pur. From the aqueous solution, hydrosulphuric acid or ferrocyanide of potassium being dropped in, a precipitate is thrown down. What is thrown down by ammonia or hydrate of potassium from the same solution is white, and is redissolved by either precipitant in excess. The precipitate thrown down by the carbonate of either ammonium or potassium is (also) white, but is not redissolved when these are added in excess.

Uses, &c. Dry chloride of zinc is chiefly used as a caustic, for which it is highly recommended by Voght, Canquoin, and others. It is more powerful than chloride of antimony, and its action extends deeper than does nitrate of silver, whilst it exercises an influence over the vital actions of neighbouring parts. The sore is generally healthy after the separation of the eschar, and no constitutional disorder ensues. It has been given in scrofula, epilepsy, chorea, &c.; and, combined with hydrocyanic acid, in facial neuralgia.—Dose, ¹⁄₂ gr. to 2 gr.; externally, as a lotion, 2 to 3 gr. to water, 1 oz. In large doses it is poisonous.

The solution is also used as a caustic, but chiefly as a disinfectant and deodorizer, e.g. as Sir Wm. Burnett’s Fluid and Professor Tuson’s ‘Sporokton,’ of which it is one of the very best, possessing, as it does, the power of rapidly decomposing sulphide of ammonium and of rendering inert the virus of infectious diseases.

Zinc, Cy′anide of. ZnCy₂. Syn. Cyanuret of zinc; Zinci cyanidum, Zinci cyanuretum, L. Prep. (P. Cod.) Add a solution of cyanide of potassium to another of pure sulphate of zinc; wash, and dry the precipitate.—Dose, ¹⁄₈ to 1 gr., twice a day; in epilepsy, hysteria, and other nervous affections, heartburn, worms, &c.; and as a substitute for hydro-cyanic acid.

Zinc, Ferrocy′anide of. Zn₂FeCy₆. Syn. Zinci ferrocyanidum, L. Prep. By adding a hot solution of ferrocyanide of potassium to a hot and strong solution of pure sulphate of zinc, and washing, and drying the precipitate. White.—Dose, 1 to 4 gr.; in the same cases as the last.

Zinc, I′odide of. ZnI₂. Syn. Hydriodate of zinc†; Zinci iodidum, Zinci hydriodas, L. Prep. 1. (Duflos.) Iodine, 2 parts; granulated zinc, 1 part; water, 4 parts; proceed as for ferrous iodide, only employing a glass or porcelain vessel.

2. (Magendie.) Iodine, 17 parts; zinc (in powder), 20 parts; mix, and sublime in a matrass.

Prop., &c. Deliquescent. Chiefly used externally; 15 gr. to water, 6 fl. oz., as a collyrium in scrofulous inflammation of the eye (Poulet); 1 dr. to lard, 1 oz., as a powerful resolvent in scrofulous and other glandular swellings, rubbed on the part twice a day. (Ure.)

Zinc, Lac′tate of. Zn(C₃H₅O₂)₂. Syn. Zinci lactas, L. Prepared from zinc in the same way as ferrous lactate is from iron.

Zinc, Ox′ide of. Syn. Protoxide of zinc; Zinci oxydum (B. P., Ph. L., E., & D.), L. Prep. 1. (Ph. L.) Sulphate of zinc (pure), 1 lb.; carbonate of ammonium, 6¹⁄₂ oz.; dissolve each separately in 6 quarts of water, filter, mix the solutions, well wash the precipitate with water, and calcine it for 2 hours in a strong fire. The Ph. E. is nearly similar.

2. (Ph. D., B. P.) Place carbonate of zinc in a covered clay crucible, and expose it to a very low red heat, until a portion taken from the centre of the mass ceases to effervesce on being dropped into dilute sulphuric acid.

Prop., &c. A white, tasteless powder; insoluble in water; freely soluble in acids, the solution yielding colourless and easily crystallisable salts; strongly basic.

Uses, &c. It is tonic and antispasmodic, and has been advantageously used in chorea, epilepsy, and other nervous and spasmodic affections.—Dose, 1 to 6 gr., twice a day. It is also used as a dusting powder, and to make an ointment. It has been proposed as a substitute for white lead in painting, than which it covers better, but dries slower, and hence requires the addition of dried white vitriol. This oxide is the only compound which zinc forms with oxygen.

Zinc, Phosphide. Fragments of pure distilled zinc are introduced into a tubulated stoneware retort, so as to occupy about one fourth of its capacity; the retort is placed in an ordinary furnace, and a current of dry carbonic acid is passed into it through the neck. Over the tubulure is placed a crucible cover, so as to close the orifice incompletely, and allow the carbonic acid, after traversing the retort, to escape. When the zinc enters into ebullition, small fragments of previously-dried phosphorus are successively thrown in through the tubulure. The cover is removed and returned after each addition to prevent loss of phosphorus. From time to time it is necessary to break the crust of phosphorus formed, in order to expose a new layer of metal to the action of the phosphorus. The operation is terminated by increasing the heat strongly—a precaution that is indispensable, in order to separate as completely as possible the zinc phosphide from the metallic button of nearly pure zinc, which collects at the bottom of the retort. Further, the zinc phosphide should be reduced to very fine powder, and the fragments which resist the action of the metal, however slightly, should be reserved for another operation. The product pulverises the more readily in proportion as it approaches more closely the formula P₂Zn₃. In this state it resembles iron reduced by hydrogen, and only thus should it be used by pharmaceutists. It is completely soluble in hydrochloric acid.[274]

Zinc, Sulphate of. ZnSO₄. Syn. White copperas*; White vitriol*; Zinci sulphus (B. P., Ph. L., E., & D.), L. Prep. 1. (Ph. L.) Granulated zinc, 5 oz.; diluted sulphuric acid, 1 quart; dissolve, filter. Evaporate to a pellicle, and set it aside to crystallise.

2. (Ph. D.) Zinc (laminated or granulated), 4 oz.; sulphuric acid, 3 fl. oz.; water, 1 pint; mix in a porcelain capsule, and, when gas ceases to be evolved, boil for 10 minutes, filter through calico, and evaporate the filtrate to dryness; dissolve the dry salt in water, 1 pint; frequently agitate the solution, when cold, during 6 hours, with prepared chalk, ¹⁄₄ oz.; next filter, acidulate the filtrate with nitric acid and dilute sulphuric acid, of each 1 fl. dr.; evaporate until a pellicle forms on the surface, and set it aside to crystallise; dry the crystals on bibulous paper, without heat, and preserve them in a bottle. More crystals may be obtained from the mother-liquor.

3. (B. P.) Pour 12 fl. oz. of sulphuric acid, previously mixed with 4 pints of distilled water, on 16 oz. of granulated zinc contained in a porcelain basin, and when effervescence has nearly ceased, aid the action by a gentle heat. Filter the fluid into a gallon bottle, and add, gradually, with constant agitation, solution of chlorine until the fluid acquires a permanent odour of chlorine. Add now, with continued agitation, ¹⁄₂ oz. or q. s. of carbonate of zinc, until a brown precipitate appears; let it settle, filter the solution, evaporate till a pellicle forms on the surface, and set aside to crystallise. Dry the crystals by exposure to air on filtering paper placed on porous tiles. More crystals may be obtained by again evaporating the mother-liquor.

4. The common sulphate of zinc of commerce frequently contains copper, cadmium, lead, iron, and manganese, and nearly always one or more of them. By digesting its concentrated solution for some time with metallic zinc, it may be freed from copper, lead, and cadmium, for these metals are all reduced and precipitated in a metallic state; or, the acidulated solution may be treated with sulphuretted hydrogen as long as any precipitate forms. In order to separate the iron, chlorine gas may be passed into the solution, by which the iron is converted into the ferrous chloride; if this solution be exposed to the air for a length of time, it absorbs oxygen, and oxide of iron is deposited as a yellow powder, from which the solution must be filtered. When the sulphate contains manganese, which is not very often the case, the solution must be boiled up a few times with purified charcoal, filtered, and evaporated. (‘Jour. für prakt. Chem.’) The product of each of the above formulæ is nearly chemically pure.

5. (Commercial.) The crude sulphate of zinc (white copperas, or white vitriol, of the shops) is prepared by roasting native sulphide of zinc (zinc blende) in a reverberatory furnace, exposing the calcined mass to the air and humidity for some time, then lixiviating it, and evaporating the resulting solution until it forms a white semi-crystalline mass on cooling.

Prop. Pure sulphate of zinc forms inodorous, colourless, transparent, quadrangular prisms, closely resembling in appearance those of Epsom salt, which effloresce slightly in the air, and contains 7 equiv. of water; it has a slightly acidulous and very styptic metallic taste; the crystals dissolve in 2¹⁄₂ parts of cold and in less than their own weight of boiling water; they are insoluble in alcohol. The crude sulphate of zinc of commerce (white vitriol) occurs in irregular granular masses, which somewhat resemble loaf sugar.

When a solution of this salt, in 6 of water, is boiled with a little nitric acid, and a solution of ammonia is then added until the oxide of zinc at first precipitated is all redissolved, no yellow precipitate remains, or a trace only, and the solution is colourless.

Uses. In medicine, as a tonic, antispasmodic, &c.; in doses of 1 to 2 gr., twice daily; as an emetic, 10 to 30 gr. In large doses it is poisonous. It has been employed with benefit in dyspepsia, fluor albus, chorea, epilepsy, hooping-cough, and other convulsive and nervous affections, generally combined with bitters, foxglove, hemlock, henbane, or opium. As an emetic, it acts almost immediately, and is therefore well suited to empty the stomach at the commencement of a fit of ague, and in cases of poisoning, &c. It is also extensively used externally, to form astringent and repellant collyria, injections and lotions.

Zinc, Sulpho-carbolate. The acid prepared as in sulpho-carbolate of soda (which see) is saturated by aid of a gentle heat with oxide of zinc, filtered, and crystals allowed to form. The crystals should be dried by exposure to the air.

Zinc, Vale′′rianate of. Zn(C₅H₉O₂)₂. Syn. Zinci valerianas (B. P., Ph. D.) Prep. (Ph. D.) Valerianate of sodium, 2¹⁄₂ oz., and sulphate of zinc, 2 oz. 7 dr., are each separately dissolved in distilled water, 1 pint; the solutions are then heated to 200° Fahr., mixed, and the resulting crystals skimmed off; the liquid is next evaporated at a temperature not higher than 200°, until it measures 4 fl. oz., the crystals, as they form, being removed from the surface; the salt thus obtained is steeped, for an hour, in distilled water, just sufficient to cover it, after which the whole is transferred to a paper filter, on which it is at first drained, and then dried at a heat not exceeding 100°.

Prop., &c. Brilliant white, pearly scales; very light; astringent; smells strongly of valerianic acid; only slightly soluble in cold water, more so in hot water, and freely soluble in alcohol and ether; exposure to heat rapidly decomposes it; exposure to the air also decomposes it, but more slowly. It is regarded as powerfully antispasmodic and tonic.—Dose, 1 to 3 gr., thrice daily, made into pills; in neuralgia, tic douloureux, nervous headaches (more particularly hemicrania), hysteria, palpitation of the heart, vertigo, chorea, epilepsy, &c.

Obs. Butyrate of zinc, scented with valerianic acid, which is often sold for the above compound, may be detected by distilling it with sulphuric acid; the distillate, tested with a strong solution of acetate of copper, gives a bluish-white precipitate if it contains butyric acid. The valerianate is distinguished from the other salts of zinc by its extreme lightness.

ZINC-E′THYL. Zn(C₂H₅)₂. A curious liquid body, discovered by Dr Frankland, and formed, along with iodide of zinc, when iodide of ethyl is heated with pure zinc in a sealed glass tube. The mixed white product, by distillation in a current of hydrogen, yields pure zinc-ethyl. It is a highly volatile liquid, having a rather disagreeable odour, and so rapidly decomposed by contact with the air that it takes fire. Water resolves it into hydride of ethyl, and other products.

ZINC-ME′THYL. Zn(CH₃)₂. Obtained by the action of zinc upon iodide of methyl, as zinc-ethyl. It takes fire on coming in contact with the air.

ZINC′ING. Syn. Zinking. Vessels of copper and brass may be covered with a firmly adherent layer of pure zinc, by boiling them in a solution of chloride of zinc, pure zinc turnings being at the same time present in considerable excess. The same object may be effected by means of zinc and a solution of chloride of ammonium or hydrate of potassium.

The variety of zinced iron commonly known by the name of ‘galvanised iron’ is prepared by immersing the sheets of metal, previously scoured and cleaned with dilute hydrochloric acid, in a bath of melted zinc covered with powdered sal ammoniac, and moving them about until they are sufficiently coated.

ZINCOG′RAPHY. An art closely resembling lithography, in which plates of zinc are substituted for slabs of stone.

ZIR′CON. See Gems.

ZIRCONIUM. Zr. Syn. The oxide of this metal, a white pulverulent earth, discovered in the mineral gargon or zircon of Ceylon, by Klaproth, in 1789. It has since been found in the hyacinth.

Prep. The stone is calcined and thrown into cold water, and then powdered in an agate mortar; the powder is mixed with 9 parts of pure hydrate of potassium, and the mixture projected, by spoonfuls, into a red-hot crucible, care being taken that each portion is fused before another is added; after fusion, with an increased heat, for an hour and a half, the whole is allowed to cool; the calcined mass is next powdered, and boiled in water; the insoluble portion is then dissolved in hydrochloric acid, and the solution heated, that the silicic acid may fall down, after which the zirconia is precipitated with hydrate of potassium; or, the zirconia may be precipitated with carbonate of sodium, and the carbonic acid expelled by heat.

From this, metallic zirconium is obtained by heating in a glass tube, with a spirit lamp, a mixture of potassium and the double fluoride of zirconium and potassium, carefully dried; the product is washed with water, and digested for some time in dilute hydrochloric acid.

Prop., &c. A black powder; it acquires a feeble metallic lustre under the burnisher, and takes fire when heated in the air. It has not been thoroughly examined.

Oxide of zirconium, or zirconia, ZrO₂, has neither taste nor odour, is insoluble in water, and forms salts with the acids. It is distinguished from all the other earths, except thorina, by being precipitated when any of the neutral salts of zirconium are boiled with a saturated solution of sulphate of potassium. The salts of zirconium are distinguished from those of aluminium and glucinium by being precipitated by all the pure alkalies, and by being insoluble when they are added in excess. The precipitated hydrate and carbonate are readily soluble in acids.

WORKS REFERRED TO IN THIS EDITION.