METALLURGY. 



i.lan was devised. The four element 

 Ln, >ulphur.and phosphorus were 



oar- 

 car- 



apa 



that a 



could diffuse 



in 



In 

 Steel 



fipfinitelv proved unit i . ,, 



tl ou'h m 1-hot iron the last objection to the 

 Carbide thec.rv seemed to have been removed 

 1 the discussion of the paper in the Iron and 

 Seel Institute some doubts were expressed as 

 to whether these investigations should be ac- 

 Mted as conclusive demonstrations. Mr. Had 

 field thought the results would be of great value 



'" thC ^"^"^ilTThe^British Iron and 

 he i)resent position of the so- 

 lutinn themv of" carbonized iron Dr. A. Stans- 

 field reached' the conclusions that the carbon in 

 molten iron is in a state of solution, and that 

 the molecule of carbon must then contain one 

 or two atoms, and is probably monatomic. ine 

 solidified iron i* in the y state and contains 

 free carbon in solution. The molecular weight 

 of thi* carbon has not been discussed, but it is 

 probably the same as that in the molten iron. 

 The carbon in solid solution combines with iron, 

 on cooling to form a carbide, which is probably 

 expressed by the formula 2(Fe,C). When, on 

 further cooling, this carbide falls out of solution 

 as cementite its formula may become more com- 

 plicatedthe solution theory affords no informa- 

 tion on this point but Sir W. Roberts- Austen 

 stated in his presidential address that the nature 

 of the products of its solution in acids led to 

 the conclusion that the molecule may contain six 

 atoms of carbon, and is at least as complex as 

 would be indicated by the formula 6(Fe ? C). There 

 appears to be a belief that the solution theory 

 is in a sense opposed and has gone far enough 

 to supplant the older allotropic theory, but the 

 paper shows that the solution theory of the rela- 

 tions of carbon and iron entirely involves the 

 allotropic changes with which the name of Os- 

 mond is connected. 



In three successive papers Baron Juptner von 

 Jorstorff has sought to apply the laws of solu- 

 tion to iron and steel. He finds that carbon is 

 dissolved as such in pure iron at a sufficiently 

 high temperature. The molecule of the dissolved 

 carbon l>etween 1,600 and 1,300 C. consists of 

 two atoms. It increases with decreasing tempera- 

 ture, and at 1,150 C. nearly equal amounts of 

 two-atom and three-atom molecules are present 

 in the solution. At a still lower temperature 

 there is in the solution, besides a certain amount 

 of free carbon increasing with the content of 

 carl>on present, iron carbide. At first the latter 

 remains in solution with the free carbon (aus- 

 tenite). If, however, its quantity increases above 

 a certain amount, the alloy separates into two 

 parts. In the one part the free carbon prevails; 

 in the other the carbide of iron (martensite) pre- 

 vails. With falling temperature the amount of 

 the iron carbide increases, as does also the mar- 

 tensite, while the quantity of the austenite de- 

 creases until at length only martensite is present. 



Iron and Steel. The use of finely divided iron 

 ore obtained by a concentrating process was de- 

 scribed in a paper by Prof. J. Wiborgh, of Stock- 

 holm, read at the autumn meeting of the Iron 

 and Steel Institute. By the introduction of the 

 methods of separation mentioned, the power of 

 enriching iron ores has been greatly increased, 

 but the advantage is qualified by the circumstance 

 that the product obtained is usually in the form 

 of fine powder, which limits its utility to the 



smelter. The paper showed how the material 

 may be utilized by direct addition to the charges 

 in the blast furnace, by agglomeration previous 

 to charging in the blast furnace, as a refining 

 or softening material in the open-hearth furnace,, 

 and for the production of sponge iron for use 

 in the open-hearth furnace. 



The " Kraft " smelting works at Stettin, Ger- 

 many, are founded on a new principle, and are 

 specially intended to produce pig iron to compete 

 with that imported from England, Sweden, and 

 Spain. The raw materials for producing the pig 

 iron are iron ore, coke, air, and flux. The carbon 

 of the coke serves three purposes in the furnaces 

 viz., to withdraw the oxygen from the iron ore, 

 to char the iron thus obtained, and to produce 

 the requisite heat. For making coke horizontal 

 furnaces with horizontal channels are used. The 

 finely powdered and washed British coal is put 

 into the furnace by means of a high gangway,, 

 and the process of distillation is so conducted 

 that it is able to stand the friction of the ore 

 in the furnace and of the blast. The gas thus 

 formed is used to heat the coke furnaces after 

 the tar has been separated by cooling, and after 

 the ammonia water has been obtained from the 

 ammonia gas by means of suitable washing ar- 

 rangements. This is manufactured into sulphate 

 of ammonia. Considerable economies are effected 

 by improvements in the arrangement and manipu- 

 lation of the furnace. Formerly the gases which 

 accumulated, and which consist of 75 per cent, 

 nitrogen, 22 per cent, coal oxide, and 3 per cent, 

 carbonic acid, were allowed to escape; now they 

 are burned under the boiler, and the coal oxide 

 is used to produce the steam for the blasts and 

 the electrical machinery. Attempts have been 

 made for some time to utilize the blast-furnace 

 slag, which consists of calcium, aluminum, and 

 silica. This has now been done,, and the slag 

 is used in large pieces or in cast blocks, which 

 are as hard as granite and have a high specific 

 weight, for streets, dikes, and bank protections. 

 The granulated slag, which is produced by run- 

 ning the liquid slag in moving water, and which 

 has a low specific weight, is used to sand the 

 pathways and pavements and as an isolating ma- 

 terial, etc. Bricks are made with this slag mixed 

 with lime, which harden in from thirty-six to 

 forty-eight hours. 



The fundamental assumption of a hypothesis 

 for the constitution of steel suggested by Prof. 

 E. D. Campbell, of Ann Arbor, Mich., is that iron 

 forms with carbon a series of compounds, which 

 might properly be termed " ferrocarbons," on ac- 

 count of their similarity in structure to hydro- 

 carbons. This series of ferrocarbons has the em- 

 pirical formula (CFe 3 )n, or CnFe 3 n, and should 

 be considered as derived from the hydrocarbons 

 of the olefine series with the general formula 

 CnH 2 n b> the replacement of the H 2 by the 

 bivalent groups Fe 3 . These ferrocarbons, dis- 

 solved in hydrochloric acid, yield as their primary 

 products of solution the corresponding defines 

 and hydrogen. 



The Demenge process of hardening steel ingots,, 

 which is in use at one of the principal steel works 

 in France, consists in directly carburizing one of 

 the faces of the ingot at the time of casting by 

 lining one of the vertical sides of the mold with 

 carburizing substances. The carburizing action 

 is prevented from penetrating too deeply into the 

 inside of the ingot by casting the vertical side 

 opposite to the carburizing side. The carburiza- 

 tion of the one face by this method is said to 

 be quite uniform. The case-hardened surface is 

 rather rough; but all irregularity disappears in 



