Zinc plate

“ Remove all the impurities from the surface of the zinc when it is melted, with a metal spoon or piece of tin. Before filling the mold with the metal, place a piece of No. 14 gauge bare copper wire through a small hole in one of the end pieces forming the mold, and allow it to project several inches inside, and make sure the mold is perfectly level. The zinc will run around the end of the wire, which is to afford a means of connecting the zinc plate to one of the binding posts forming the terminals of the cell. ”

“ As it is not easy to obtain zinc perfectly free from admixture of other metals, an artifice is commonly resorted to for obtaining a surface of pure metal, by rubbing a plate of the ordinary metal with quicksilver, which readily dissolves pure zinc, but is without action on the iron and other metals with which the zinc is contaminated, while the quicksilver is not acted upon by the diluted acid, but is merely the vehicle by which the pure zinc is presented to the liquid. ”

“ He proposes, instead of having the plates all the same width, to have one wide and one very narrow plate. This would leave a trough between the two wide plates of the depth of the thickness of the plates. He proposes to force into this trough very tightly pieces of teak, and to the teak, thus embedded, he nails a sheathing of zinc. The zinc is kept clean by slowly wearing away of its surface from action by contact with the iron and salt water.
There are four patents, in which various, so-called, non-conducting coats are put on the iron, and copper pigment in some form put on over them. ”

“ Experience shows that it is better to make them of rolled rather than of cast zinc, and to secure them on studs which can be kept bright, so as to ensure a direct metallic contact between the zinc and the boiler-plate. The function of the zinc is to set up galvanic action; it plays the part of the negative metal, and is dissolved while the metal of the shell is kept electro-positive. Care must always be taken that the fragments which break off the zinc as it wastes away cannot fall upon the heating surfaces of the boiler. ”

“ On the whole, tin-plate is a very unsuitable material for the storage and preservation of acid goods. Certain enamels, used for glazing earthenware or for coating metal cooking pots, contain lead, which they yield to the food prepared in them. Food materials that have been in contact with galvanized vessels sometimes are contaminated with zinc. Zinc is also not infrequently present in wines. ”

“ Iron is usually galvanized by dipping it into a bath of melted zinc, but electrical methods are also employed. Zinc plates are used in many forms of electrical batteries. In the laboratory zinc is used in the preparation of hydrogen, and in the form of zinc dust as a reducing agent.
One of the largest uses of zinc is in the manufacture of alloys. Brass, an alloy of zinc and copper, is the most important of these; German silver, consisting of copper, zinc, and nickel, has many uses; various bronzes, coin metals, and bearing metals also contain zinc. ”

“ Zinc is incapable of decomposing pure water; and if the zinc plates be kept moist with pure water, the galvanic pile does not act; but zinc is capable of oxidating itself when placed in contact with water, holding in solution either oxygen, atmospheric air, or nitrous or muriatic acid, &c.: and under such circumstances, the galvanic phenomena are produced, and their intensity is in proportion to the rapidity with which the zinc is oxidated. ”

“ In the mixing of lead and type-metal see that there are no pieces of zinc among it, the least portion of which will spoil the whole of the other metal that is mixed with it. Zinc is of a bluish white color; its hue is intermediate between that of lead and tin. It takes about eighty degrees more heat than lead to bring it into fusion; therefore, should any metal float on the top of the lead, do not try to mix it, but immediately take it off with the ladle. ”

“ Until the last quarter of a century, zinc was but little used, but of late it has taken the place for many useful purposes where lead was formerly used, principally owing to its cheapness and lightness. Zinc is a hard metal of a grayish colour, not easily bent but rather brittle, but when made nearly red hot, it is capable both of being rolled out into sheets and being beaten into form by the hammer. Zinc is about six-and-three-quarter times heavier than water. ”

“ The various modifications of zinciferous flue ashes from blast furnaces are an object for continual demand, being both a valuable material for the production of zinc and, in its superior qualities, a desirable pigment. In the regeneration of zinc the presence of foreign substances is of some concern; detrimental are lead, sulphur, and sulphuric acid in form of lead, zinc, and lime sulphate. ”

“ The zinc, or which is the same thing, the spelter of the shops, should be melted in a vessel which exposes but a small surface to the action of the air, otherwise it would absorb oxygen so rapidly as to be converted into the flowers of zinc.—The melted metal should be poured as soon as possible into a mould of the proper size, made of stone or brass.—It is not necessary that the plates of copper should be more than one tenth of the thickness of those of zinc. ”

“ Of the total United States zinc consumption in normal times, about 60 per cent is used in galvanizing iron and steel objects to protect them from rust, 20 per cent is used in the manufacture of brass and other alloys, 11 per cent goes into the form of rolled sheets for roofing, plumbing, etc., 1 per cent is employed in desilverizing lead bullion, and the remaining 8 per cent is used for pigments, electrodes, and other miscellaneous purposes. ”

“ It is generally recognized that the purest ores produce the purest metal. Grades of commercial zinc are usually based on selected ores, and brands, when they mean anything usually mean that the metal is made from certain ores. Chemical control of the metal purchased is not nearly as common as it should be, and the refining of zinc is at best an imperfect operation. To obtain the metal chemically pure a specially prepared pure oxide or salt of zinc is distilled. ”

“ In zinc works zinc white is always made in the manner which has been described. It may also be obtained as a by-product in another metallurgical operation, the desilverisation of lead by Parkes’ process. In this process an alloy of silver and zinc is obtained. By sending a current of superheated steam over the molten alloy the zinc decomposes the steam, hydrogen and zinc oxide being formed. The zinc white is carried by the current of gas into chambers, in which it deposits. ”

“ Second, mix red lead and granular metallic zinc, ground fine, or such a mineral as we have mentioned--crystalline and granular in its character. Put on two or three coats, and allow each to set--they will never dry hard. The zinc will slowly wear off, keeping the whole surface clean, while there will be left enough coating of the lead to preserve the iron from rust. The oil I would urge for these pigments is linseed--as little boiled as possible, to be thinned with spirits of turpentine. There seems to have been a mania for mixtures of tar and resins, their spirits and oils ”

“ Metal in thin sheets is liable only to the objection from which slate is free,—namely, that it is difficult to keep its surface from undulation in changes of temperature. In all other respects, both zinc, copper, lead, and iron, bind well with any oleaginous vehicle, and offer the great convenience that they may be cut out to any desired shape, and attached to any other kind of material by nails, screws, or even by strong cements, such as marine glue. Zinc is, perhaps, the best of all, as it cuts more readily than copper or iron, and keeps its shape better than lead ”

“ Later, when the whole apparatus has become warm, the zinc condenses to a liquid in the receiver, from which it is drawn off into molds. Commercial zinc often contains a number of impurities, especially carbon, arsenic, and iron.
Physical properties. Pure zinc is a rather heavy bluish-white metal with a high luster. It melts at about 420°, and if heated much above this temperature in the air takes fire and burns with a very bright bluish flame. ”

“ Plates of platinum and pure or amalgamated zinc are separated by a porous pot, and each surrounded by some of the same solution of a salt of a metal more oxidizable than zinc, such as potassium. When the plates are connected together by means of a wire, no current flows, and no appreciable amount of zinc dissolves, for the dissolution of zinc would involve the separation of potassium and a gain in available energy. If sulphuric acid be added to the vessel containing the zinc, these conditions are unaltered and still no zinc is dissolved. ”

“ In one group, the silver-lead deposits, zinc seems a minor factor, but with depth replaces lead as the predominant metal. Deposits of these complex ores have in recent years become important sources of zinc through recognition of the zinc ores in their oxidized zones, through zinc becoming the dominant metal with increasing depth at many mines, and especially through improvements in methods of concentrating complex ores and extracting metal from the concentrates. ”

“ The setting point of zinc being above that of lead, a zinc crust is gradually formed, and this is broken up and carefully lifted off into a small pot conveniently placed, care being taken to let as much lead drain off as possible. The fire is again applied strongly to the pot, and when the lead is sufficiently heated, a further quantity of zinc, about one-third of the whole quantity used, is added, when the same process of cooling and removing the zinc crust is repeated. ”

“ With equal amounts of zinc per unit of area, the zinc coating put on by the cold process is more resistant to the corroding action of a saturated solution of copper sulphate than is the case with steel coated by the ordinary hot galvanizing process; or, to put it in another form, articles coated by the cold process should have an equally long life under the same conditions of exposure that hot galvanized articles are exposed to, and with less zinc than would be necessary in the ordinary hot process. The hardness of a zinc surface is a matter of some importance. ”

“ Some manganese is usually present replacing zinc. It is found in the zinc mines at Sterling Hill and Franklin Furnace in Sussex county, New Jersey, where it is associated with franklinite and willemite in crystalline limestone, and is mined as an ore of zinc. Artificial crystals of a white or yellowish colour are not infrequently formed by sublimation in zinc furnaces. ”

“ Zinc is not found in a native state. This ore is in the form of an oxide, as it is called. In roasting, certain of the impurities are driven off in gases, and mixing it with charcoal or coke and then applying heat to the confined mass, causes the zinc to melt and finally go off into a gas, as we shall presently see. ”

“ The advantages of the zinc method are, that it is easily worked and that the excess of zinc is readily removed by simply filtering. The disadvantages are the slowness [68] with which the last portions of ferric iron are reduced, the danger of loss by effervescence, the precipitation of basic salts, and, perhaps, of iron, and the loading of the solution with salts of zinc, which in the titration with bichromate have a prejudicial effect. ”

“ No zinc is used, only care in washing out, drying out, and managing the water." This is the evidence of an engineer with a large number of vessels in his charge. On the other hand, some of the most prominent Liverpool engineers always use zinc, and take care to apply it most strictly. The evidence of one of them is as follows: "We always fix slabs of zinc to most boilers, exposing not less than a surface of one square foot for every twenty indicated horse-power, and distributed throughout the boiler. This zinc we find to be in a state of oxide and crumbling away in about three months. ”

“ Preparation of pure Oxide of Zinc, by M. Hermann.—It is by no means easy to obtain this substance perfectly pure; the following is M. Hermann’s process: Oxide of zinc, or metallic zinc, is to be dissolved in excess of sulphuric acid, and the solution being filtered, sulphuretted hydrogen is to be passed through, so long as a brown or yellow precipitate is formed. Cadmium, lead, or copper, being thus separated, and the solution filtered, it is to be treated with solution of the chloride of lime, (bleaching powder,) by which the iron and manganese will be separated. ”

“ The inconvenience arising from the brittleness of the zinc being removed, this metal is applicable to many useful purposes. It may even be drawn into wire, but the tenacity of this is not great: a piece of zinc wire, one tenth of an inch in diameter, will sustain only a weight of twenty-six pounds without breaking. It has been proposed to substitute zinc in the place of tin for the lining of copper vessels ”

“ Many silicates containing magnesium are known and some of them are important substances. Serpentine, asbestos, talc, and meerschaum are examples of such substances.
ZINC
Occurrence. Zinc never occurs free in nature. Its compounds have been found in many different countries, but it is not a constituent of common rocks and minerals, and its occurrence is rather local and confined to definite deposits or pockets. It occurs chiefly in the following ores:
One fourth of the world's output of zinc comes from the United States, Missouri being the largest producer. ”