ogen gas a ark powde in contac reduction -mass of a eating the de of iron lead, and vered clay the wire is impurities ition of a! of silvery! annealing phur in pig-iron tends to the production of the white var The surface and fractured portions often exhibit b patches, which are characteristic of sulphur in iron. Fer sulphide, heated with carbon, is but little affected, it is decomposed at a high temperature by oxidising stances. When this sulphide is heated with ferrous phate in suitable proportions, the whole of the sulphu removed as sulphurous acid SO2, leaving ferric oxide Fe Iron and Phosphorus.-These bodies readily when phosphorus is dropped into red-hot iron, formin phosphide of iron Fe12P. When oxide of iron is red in the presence of an earthy phosphate, phosphor separated, and unites with the iron. 3 per cent of 1 phorus in wrought-iron makes it harder and some diminishes its tenacity. 5 per cent makes it cold-s but not red-short. 1 per cent makes it very brittle. effect of phosphorus on iron is, to impart a coa crystalline structure, diminish its strength, increase fusibility, and make it cold-short. The presence of 1 phorus in cast-iron diminishes its strength, but on acc of its imparting fluidity to the metal, its presen beneficial in making fine castings. Iron and Arsenic. The effect of arsenic on iron is r the same as that of sulphur, a very small amount will the metal red-short. Several compounds of iron and ar are known, varying from gray to white in colour. Ar is not a very frequent impurity in iron. Iron and Silicon.-A compound of silicon and highly crystalline, and of a silver-white colour, know silicon iron, is now an article of commerce, and is used producing soundness in steel castings. It is obtaine reducing silica with carbon in the presence of iron. be heated alone with silica no action takes place. effect of silicon on cast-iron is to set the combined ca free, so that, as a rule, the grayer the pig, the higher amount of silicon present. Silicon makes iron hard, easily fusible, and brittle. If Iron and Carbon.-Carbon unites with proportions up to about 41 per cent, formi varieties of steel and cast-iron. When man a larger proportion of carbon may be t difference between malleable-iron, steel, a chiefly dependent on the relative amount combination with the iron. The more harder and more fusible the metal becomes, is considerably increased by the presence c such as phosphorus, sulphur, etc. Combina when iron is heated in contact with gaseou carbonic oxide, cyanogen, and hydrocarbons longed exposure to a high temperature in co carbon, such an operation being termed cemer the carbon present in iron reaches 15 per c sensibly harder; this may be considered the of carbon which can be present in malleab diminishing its softness and malleability. considered as iron containing from 15 to carbon. When the proportion of carbon is l termed "mild steel," and in like manner higher proportions of carbon are termed Carbon exists in pig-iron in two states-free When the carbon is chiefly in the combined is "white." On the other hand, when the being diffused through the iron in crystalline is called "gray"; but neither variety is ent graphite or combined carbon respectively. In the carbon is partly combined and partly fre to the fractured surface of the metal a speckle consisting of gray spots, enclosed by reticul white; it is then termed "mottled iron.” Chromium is a comparatively rare meta occurs in nature in combination with other elem ore being chrome-iron-stone FeO, Cr,Og. Chr oxides, forms the colouring matter of several green colour of the emerald, for example, is du in various e different is present up. The st-iron is carbon in! kes place such as y a pro with solid When e iron is Camount without be may Der cent metal is ith the steels." mbined. the iron is free, the iron ee from arieties gives arance, nes of oxide. The metal is obtained by the reduction of its or chloride, or by the electrolysis of its chlorides, chromium separates out in brittle glistening scales. tin-white in colour, having a specific gravity of 6.8. fused metal is said to be as hard as corundum; it with more difficulty than platinum, and is only s oxidised when heated in air. It is used in the form alloy with iron and carbon, forming a hard, white, brilliant steel, much esteemed for special purposes. Manganese. The pure metal, obtained by the redu of its oxide, is a gray or reddish-white body, hard, brittle; its specific gravity is about 8; it oxidises readily than iron, and must therefore be excluded from by keeping it under rock-oil, or in sealed vessels. Its use is in the formation of alloys with iron, steel, and co It is not used in the unalloyed state. Compounds o metal are very widely distributed in nature; one of the common is pyrolusite or black oxide of manganese MnC Nickel. This is a brilliant-white, malleable, du weldable, and very tenacious metal, with a melting only a little below that of iron, but the presence of c and other impurities considerably lower its fusing Its specific gravity is 8.9; it is magnetic like iron, but less degree. It does not readily oxidise in air at ord temperatures, but when heated the monoxide NiO is fo It readily unites with sulphur, forming nickel sulphide which is brass-yellow in colour; and with arsenic, for nickel arsenide NiAs. Nickel is found in commerce in the form of dull-gray or cubes, and by melting these at a high temperature a pact, silver-white metal is obtained. The malleability of allows of its being fashioned into various articles, which sess great lustre, hardness, and durability. These prop render it valuable for coating base metals by the p of electro-plating, especially as it is little liable to oxid Commercial nickel was formerly very impure, due presence of carbon and other bodies, which make it har D brittle. Dr. Fleitmann and other metallurg simple and effective means of refining nickel, which are now largely practised. to the melted metal minute quantities o several charges, and well stirs each time One ounce of magnesium is sufficient for re impure nickel. The magnesium is suppose occluded carbonic oxide CO forming magne the carbon to separate out as graphite. readily with most metals forming alloys, so of great commercial utility. The most impo German silver. Nickel occurs in nature as copper-nickel NiAs, which is a copper-red c with a metallic lustre. As nickel pyrites brass-yellow in colour. As nickel-glance, wh compound of nickel, arsenic, and sulphur. which is a hydrated silicate of nickel, iron, a Cobalt. This metal resembles nickel in properties, and is generally associated wit Cobalt is a white metal, highly malleabl tenacious; its specific gravity is 8.9; it i nickel; almost unalterable in air at ordina but oxidises when heated, and at a high ten with a red flame. It is seldom used in the m its compounds are largely employed in pigm with arsenic to form iron-gray, fusible, and bri The principal ores are smaltine CoAs Co,ASS, and cobalt bloom (Co,AsО4,4H2O). ZINC GROUP. ZINC, CADMIUM, AND § 10. Zinc, commonly known by the nar when in the cast state, is a white metal, with and bright metallic lustre. Ordinary zine is b and when fractured exhibits a highly crysta When pure it is malleable at the ordinar while commercial cast-zinc is brittle; the 1 ve devised Dughenin ann ad nesiumi is added 60 lbs. of educe the 1 to caus of these is Carnierite SIUM pelter 1 shade, brittle, ucture. rature, wever. becomes malleable and ductile if heated to a temperat 100° to 150° C., but beyond that point it again be brittle. Its specific gravity in the cast state is 6.9, 1 may be increased to 7.1 by rolling or forging; it cont but slightly on cooling from the liquid state, and is well adapted for castings. The castings made at a temperature are brittle and crystalline; but when cast the solidifying point are more malleable. Zinc mel 412° C. and boils at 1040° C. At a red heat in air it ra oxidises, and burns with a greenish-white flame, forming oxide ZnO; if raised to a bright-red heat in a closed v it may be readily distilled. When rolled zinc is expos air and moisture a gray film of suboxide is formed, v preserves the metal from further oxidation. Ordinary readily dissolves in dilute hydrochloric and sulphuric a while the pure metal is unaffected; both kinds dissolv nitric acid and in alkalies. Zinc displaces silver, platinum, bismuth, antimony, tin, mercury, and lead their solutions. The chief impurities of the comme metal are iron, lead, and arsenic. Zinc and sulphur do not readily unite, but when a mix of finely divided zinc and sulphur is projected into a re crucible, some zinc sulphide ZnS is formed. It is also for by heating zinc with cinnabar HgS. Zinc forms compounds with phosphorus and ars when these bodies are heated with it, having a met lustre and somewhat vitreous fracture. The chief ores of zinc are :-The oxide ZnO called zi or red oxide of zinc, which is white when pure, but gene red from the presence of oxide of manganese. The sulp ZnS, known as "blende" and "black jack," is the cipal source of the metal, and generally black or yellow black in colour, but sometimes it has a reddish tint from presence of galena; when pure it is white, and contains 6 per cent of zinc. The carbonate ZnCO, called calan And the silicate (2ZnO,SiO2, OH) called electric calan Zinc forms with other metals a most important clas |