METALS-METALLURGY. 



of the sulphide of iron is decomposed, and much 

 sulphurous and other acids have formed and 

 escaped in fumes. In the second, the calcined 

 ore is melted along with siliceous slags obtained 

 in later stages of the process. Here a fusible 

 slag, consisting in great part of silicate of iron, 

 is formed, and the sulphides of iron and copper 

 are run off as a regulus, termed coarse metal, 

 and granulated in water. In the third, the coarse 

 metal is calcined again for twenty-four hours, dur- 

 ing which time most of the sulphide of iron is 

 converted into oxide. In the fourth, the calcined 

 coarse metal is melted with slags rich in oxide of 

 copper, and also with rich ores, as oxide and car- 

 bonate. These oxidise any sulphide of iron 

 remaining, and a regulus called white metal is 

 formed, consisting almost entirely of disulphide of 

 copper, and containing about 75 per cent, of the 

 metal. In \hzfifth, called 'roasting,' the regulus 

 is very slowly melted, so as to allow of the gradual 

 and thorough reduction of the disulphide by heated 

 atmospheric air through the formation of oxide of 

 copper. When oxide and disulphide of copper are 

 heated together, they decompose each other, the 

 sulphur escapes as sulphurous acid, and impure 

 metallic copper, called blister copper, is produced. 

 In the sixth, the copper from the previous opera- 

 tion is refined. To effect this, it is melted in a 

 furnace, and exposed to the oxidising influence of 

 the air for from fifteen to twenty hours, by which 

 time it is full of dioxide, and this is in turn 

 reduced by throwing pure coal on the surface of 

 the molten metal, and then stirring it with a pole 

 of green birch-wood. For the last ten years the 

 produce of copper ore from British mines has 

 been steadily decreasing. In 1871, the total 

 ore raised amounted to 97,129 tons, yielding 

 6280 tons of copper, the value of which was 

 .475,143 ; but for the year 1880, the figures were 

 little more than half. Large quantities of foreign 

 and colonial ores are now, however, smelted at 

 Swansea ; and further, there has been, during the 

 past decade, a gradually increasing yield of 

 copper from the pyrites employed to make sul- 

 phuric acid in chemical works. The total quan- 

 tity of copper ore smelted in England and Wales 

 in 1871 was 399,624 tons, yielding 29,953 tons 

 of copper. 



Copper is used for a great variety of purposes. 

 Wanting in the strength of iron, it has yet the 

 advantage over that metal of not being acted on 

 by moist air or pure water, but solutions of the 

 chlorides sea-water, for example gradually cor- 

 rode it. Nevertheless, it has been very largely 

 employed as a protective sheathing for the 

 bottoms of wooden ships. Boilers, stills, cooking- 

 vessels, pipes, wire and wire-cloth, nails, spikes, 

 and many other articles, are made of copper, 

 and used in circumstances where iron, through 

 its tendency to rust, would scale away, or stain 

 objects brought into contact with it. A very 

 large quantity of copper is used for engraving 

 pictures and designs upon. Copper is admirably 

 adapted for producing works of art in electro- 

 deposit instead of casting them. This process is 

 now extensively employed, and does even for 

 objects as large as life-size statues. In this way, 

 too, iron castings can be coated thinly over with 

 copper, and this, when darkened, forms the most 

 durable imitation of bronze. Some compounds of 

 copper produce green and blue pigments, and 



others are used for imparting green and red 

 colours to glass and pottery. 



Not less important than the applications of 

 copper itself are those of its alloys. Brass, which 

 consists of copper and zinc in varying proportions, 

 but very generally of two parts of copper to one of 

 zinc, is widely employed. Articles of all kinds are 

 made of it on an enormous scale in Birmingham. 

 Brass is not only cheaper than copper, but it is 

 harder, and resists atmospheric influences better. 

 It is also more easily fused, and, with carefully pre- 

 pared moulds, produces very sharp castings ; it is 

 highly malleable and ductile, so that it can be ham- 

 mered, stamped, or drawn into wire with facility ; 

 and it has an agreeable colour, which, however, soon 

 blackens if not protected by a coating of lacquer. 

 Dutch-metal, ormolu, pinchbeck, Mannheim gold, 

 and prince's metal, are all varieties of brass. 

 Bronze, gun-metal, bell-metal, and speculum metal 

 are alloys of copper and tin. 



Iron. 



From a comparatively early period, this happily 

 abundant substance has been recognised as by far 

 the most important and indispensable of all metals. 

 Yet there was a time when bronze did service in 

 its stead, and gold, silver, and copper are of older 

 renown. But even since Dr Ure, writing in 

 1839, sa id that 'iron accommodates itself to all 

 our wants, our desires, and even caprices/ what 

 extraordinary changes have been worked through 

 new applications of iron ! Railways, and engineer- 

 ing works connected with them, merchant and 

 navy ships, artillery and war materiel, are now, 

 through the aid of the steam-hammer and numer- 

 ous improvements in the manufacture of the metal, 

 constructed on a scale and in a manner not even 

 dreamed of thirty years ago. 



Chemically pure iron can only be prepared, and 

 that with difficulty, by careful processes on a small 

 scale in the laboratory. A very high authority on 

 metallurgical subjects, Dr Percy, states that the 

 only pure iron which he has seen is that deposited 

 from solution by electrolysis. It has a grayish- 

 white colour, is susceptible of a high polish, and 

 has a specific gravity of 8-139. It differs from the 

 purest commercial iron in not having its mallea- 

 bility affected by rapid cooling after being raised 

 to a high temperature, and also in conducting 

 electricity better. Samples of perfectly pure iron, 

 however made, ought not, of course, to differ in 

 quality or in properties ; and the fact that there 

 are so many commercial qualities of malleable 

 iron varying but slightly after all in the proportion 

 of impurities they contain, and yet differing greatly 

 in value, proves that our manufacturing processes 

 are far from being perfect All high-class iron is 

 either obtained from the purest ores and fuel, or 

 the manipulations through which it passes are 

 very tedious and laborious. 



Except in one or two instances, which arc 

 scarcely free from doubt, native iron of terrestrial 

 origin has not yet been found. Meteoric iron may 

 therefore be regarded as the only form of the 

 native metal, and is usually rather an alloy of iron 

 and nickel than pure iron. A few of these meteor- 

 ites have been discovered, weighing from 1000 to 

 fully 30,000 Ibs. 



Iron ores are abundantly distributed over the 

 surface of the globe, and occur in every geological 



