440 



METALLURGY. 



tary bodies may occur, which, however, can not 

 well be differentiated by our present compara- 

 tively coarse analytical methods. Admitting 

 this, or, more correctly, that, as urged by Crookes, 

 an element may have more than one atomic 

 weight, the accepted atomic weight being the 

 mean of these, with the periodic law for our 

 guidance, and also attaching due weight to the 

 relations existing betwixt the weight and volume 

 of the atoms, it would seem that the theory of 

 the formation of homogeneous bodies by fusion 

 is in accordance with the periodic law, etc., gov- 

 erning the genesis of the elements. This is 

 equivalent to saying that a fourth state of com- 

 bination may be imagined which is not solution 

 of one metal in another, or chemical combina- 

 tion of bodies, or intermixture of bodies. We 

 may even assume that the fourth state indicates 

 a species of combination even more intimate than 

 the chemical combination of the chemists. Many 

 of our most eminent metallurgists and men of 

 science have, " by different modes of investiga- 

 tion," come to the conclusion that iron itself is 

 a very complex compound body. It is true that 

 we have merely indirect proof of this, but it only 

 remains to find methods of isolating these bodies 

 from one another. 



Several forges of the Catalan type are still op- 

 erated in Mexico. Four of them, according to 

 Mr. E. V. Wilkes, are at Oajaca forges of the 

 most primitive Catalan type, using a water blast 

 and hammers of a crude form. The master 

 workmen are brought from Catalonia, Spain. 

 The forges are each equipped with 2 or 8 fires 

 and from 1 to 3 hammers, and have an annual 

 capacity of from 300 to 400 tons of bar iron. 

 The ore used at 2 of the forges is a 55 per cent, 

 hematite, with which about 250 bushels of char- 

 coal are used in producing a ton of iron. At 

 the other 2 forges, magnetic ore containing about 

 70 per cent, of iron and hematite ore containing 

 50 per cent, are used, with a consumption of 200 

 bushels of charcoal to the ton of iron. 



In the Lebedieff direct process for producing 

 iron and other metals from their ores the metal- 

 lic oxides are brought in contact with a strong 

 base (potash, soda, lime, or dolomite), by either 

 melting the two in a finely divided state, or by 

 roasting such mixture in furnaces, provided with 

 a powerful air blast, with frequent stirring of 

 the mass. To hasten the process, common salt 

 or niter may bo added to the roasted mixture. 

 Some combinations of metallic oxides with alka- 

 lies may be produced by the wet process for 

 example, alkaline aluminates. Abstracting the 

 pure metals may then proceed in cupolas, open 

 hearths, or in crucibles in reverberatory furnaces. 

 To the mixture prepared as above are added 

 charcoal, coke, etc., as well as a proper amount 

 of siliceous materials to produce slag upon the 

 reduction of the metals. In the reduction of iron 

 and other metals easily separated by coal, etc., 

 gas, under proper pressure, containing a suffi- 

 cient amount of C0 2 , H. or C 4 H 6 . may be used 

 instead of coal, etc. After properly heating the 

 furnace, the carefully mixed oxides and bases, or 

 the oxides treated with bases, are introduced and 

 heated until thoroughly melted, when the reduc- 

 ing gases are allowed to penetrate the mass. In 

 proportion to the relative reduction of the metal 

 and separation of the bases, a further thin layer 



of oxides is added. These latter combine readily 

 with the free base and melt, and the gas then 

 again reduces the metal^the base is again sepa- 

 rated, and thus the process continues. 



The Ehrenwerth process for producing fluid 

 iron direct from the ore depends upon the fact 

 that carboniferous iron reacts in the highly 

 heated liquid condition on liquid ferriferous slag 

 and melted iron in such a manner that by the 

 carbon contained in the metal iron is reduced 

 from the slag and then unites with the metal 

 already obtained. The process continues till 

 the carbon of the reducing metal is exhausted. 

 On the other hand, fluid iron readily takes up 

 carbon again, and is saturated therewith, accord- 

 ing to the temperature, up to nearly 5 per cent. 

 It is thus possible to render decarbonized metal 

 immediately rich again in carbon. As this car- 

 boniferous metal is now capable of extracting 

 iron from the ores, it is clear that by repetition 

 of the process of the reaction of liquid carbonif- 

 erous metal on fluid ores and the recarbonizing 

 of the decarbonized metal, any desired quantity 

 of iron in the liquid condition, as ingot iron or 

 ingot steel, can be obtained direct. In order to 

 carry out this process there is necessary, however, 

 a preliminary if possible, highly carbonized 

 metal bath. To promote the rapid issue of the 

 process, very high temperatures are necessary. 



In the Middlesborough district, England, ac- 

 cording to Thomas Turner, about 63 hundred- 

 weight of raw stone are needed to yield a ton of 

 iron. The stone being calcined before it is put 

 into the furnace, is reduced to about 48 hun- 

 dredweight. In addition to this roasted iron ore, 

 about 12 hundredweight of limestone is added to 

 act as a flux, while about a ton of coke is used as 

 fuel. No less than 5 tons of atmospheric air are 

 required to burn this fuel, and this has to be 

 previously heated to redness. The product of 

 the action of the blast furnace, in addition to 

 the ton of iron, is about \\ ton of slag and G-J- 

 tons of waste gases. The blast furnace is the 

 most economical apparatus, from a thermal point 

 of view, that we possess. It was formerly thought 

 that the ore was reduced by the direct action of 

 the fuel ; but a more careful investigation has 

 shown the great importance of the furnace gases, 

 and it is recognized that, in order to get complete 

 reduction of the ore in a coke furnace, the pro- 

 portion of carbonic dioxide in the waste gases 

 should not exceed about 12 per cent. When char- 

 coal is used as the fuel a large proportion of car- 

 bonic dioxide may be permitted. 

 _ Investigation as to the cause of the produc- 

 tion of colors in tempering iron shows it to be 

 due to the formation of thin films of oxide on 

 the surface of the metal when it is heated in the 

 presence of air. It also appears from recent re- 

 searches that the oxide so produced is practically 

 transparent, first, because the sequence of colors 

 is what would be expected in films of a trans- 

 parent susbtance when the thickness of the films 

 gradually increases ; also, because of observations 

 on the reflected light, the color of which varies 

 somewhat at different angles ; but chiefly be- 

 cause it is found that on increasing the tempera- 

 ture a little above the point necessary to produce 

 a dark blue the color gradually disappears, and 

 the surface, though covered with more oxide, 

 becomes almost colorless again. The colors 



