IRON. 



which is ascertained by proof bars, so 

 disposed as to be taken out from time to 

 time. The cementation is finished on 

 the sixth day; that is to say, it commonly 

 lasts five times four-and-twenty hours. 

 And, accordingly, the workmen take one 

 of the proofs out on the fifth day, which 

 is forged, hardened r and examined by the 

 fracture. If it break short, and shew no 

 indications of iron, the fire of the furnace 

 is suffered to go out. But if it contain 

 iron, the five is kept up for twelve or 

 twenty-four hours, accordingly as the 

 quantity of fibrous iron may have proved 

 greater or less in the f<irst proof. A se- 

 cond proof bar, taken out at the proper 

 time, serves to direct them in the same 

 manner with regard to their operations. 

 By this management the cementation is 

 continued somewhat beyond the time re- 

 quisite for the entire conversion. For 

 there is less inconvenience attending a 

 slight degree of excess in the cementa- 

 tion, than would result from a portion of 

 iron remaining in the steel. The char- 

 coal after cementation is as black, and 

 apparently in the same state, as it was 

 before. M. Duhamel moistened it, and 

 applied it to the same use a second time: 

 it answered the purpose, but so much 

 more slowly, that he objects to the use of 

 it in manufactories. From this, as well 

 as other circumstances attending the 

 steel-making process, it seems advantage- 

 ous, at least with regard to expedition, 

 that the coals should contain volatile mat- 

 ter. And hence, the superior advantag- 

 es of animal coal, such as the coal of lea- 

 ther, or the hoofs and horns of animals, 

 imperfectly burned, which are used in 

 case-hardening, though they may be less 

 applicable to the longer process of steel- 

 making, for various reasons. 



M. Duhamel advises to have two tilting 

 hammers; one of the weight of one hun- 

 dred and fifty pounds, and the other half 

 that weight; the first for the purpose of 

 forging large works, and the latter small 

 bars for cutlers. He recommends another 

 small hammer of about twelve pounds, 

 for forging bars still smaller, to make 

 gravers, small files, and the like. The 

 steel must not be heated beyond the de- 

 gree of cherry-red for forging. The tilt- 

 ing hammers should give at least three 

 hundred strokes in a minute. 



The cast steel of England is made as 

 follows : a crucible about ten inches high, 

 and seven in diameter, is filled with ends 

 and fragments of the crude steel of the 

 manufactories, and the filings or frag- 

 ments of steel works. They add a flux, 



the component parts of which are usm 

 concealed. It is probable, however, that 

 the success does not much depend upon 

 this flux, which, from the quality of the 

 cast steel itself, may be presumed to be 

 of the nature of a steel cement. This 

 crucible is placed in a wind furnace like 

 that of the founders, but smaller, because 

 intended to contain one pot only. It is 

 likewise surmounted by a cover and 

 chimney, to increase the draught of air. 

 The furnace is entirelv filled with coke 

 or charred pit-goal. Five hours are re- 

 quired for the perfect fusion of the steel. 

 It is then poured into long square or oc- 

 tagonal moulds, each composed of two 

 pieces of cast iron fitted together. The 

 ingots, when taken out of the moulds, 

 have the appearance of cast iron. It is 

 then forged in the same manner as other 

 steel, but with less heat and more pre- 

 caution, because more liable to break. 



This cast steel is almost twice as dear 

 as other good steel. M. Duhamel says 

 that it is not proper for all kinds of work, 

 particularly those which require much 

 tenacity, as well as hardness, to resist 

 violent blows and strains ; but it is good 

 for razors, knives, and all toys and small 

 work which require an exquisite polish. 

 It does not seem, however, that the tena- 

 city of this steel is inferior to that of the 

 best of the other kinds, and its uniformi- 

 ty of texture is for many works an invalu- 

 able advantage . It is daily more and more 

 used in England, and must necessarily be 

 excluded from many works of considera- 

 ble size, on account of the facility with 

 which it is degraded in the fire, and the 

 difficulty of welding it, which cannot be 

 done in the common way. We have 

 been informed, that the faces of anvils 

 and broad hammers for the use of silver- 

 smiths and other artists have been made 

 of cast steel, and welded to iron by a 

 particular management, which consisted 

 in substituting between the iron and the 

 steel another kind of steel, in the form of 

 filings, or a thin plate. The steel plate 

 intended for the face xvas made as hot as 

 could be done with safety, and the iron 

 being at the same time brought to the 

 welding heat, was applied to the steel, 

 and quickly united by hammering. 



When we consider the operations by 

 which crude iron is brought into the mal- 

 leable state, then converted into steel, 

 and afterwards into a fusible metal, which 

 is not malleable, we may perceive that 

 steel-making is a kind of inversion of 

 the process of refining iron, as practised 

 in the first instance. When the oxide of 



