902 STEEL 



Hardening and tempering steel is a delicate operation. Small articles of cutlery are 

 usually hardened by first heating them to a red heat and plunging them in water ; 

 saws and such articles are, when heated, plunged into oil. All articles are tempered 

 by carefully heating them when hardened, and the degree of temper is indicated by a 

 change in the colour of the surface, which is first straw-coloured, then blue, and deep 

 blue : colour is thus made the most delicate test for the degree of temper given : after 

 this operation, steel is found to expand a little. Alloys of steel have been very care- 

 fully made by Messrs. Stoddart and Faraday ; but it can hardly be said that any alloy 

 has at present been found to give any addition to the intrinsic quality of steel. The 

 empiric titles of ' silver steel,' ' meteoric steel,' &c., may be regarded simply as fanciful 

 names to recommend the article, either as a raw material, or in a manufactured state. 



Those articles called ' run steel ' are made by melting pig-iron and pouring it into 

 moulds of sand in which the required article has been moulded ; they are then packed 

 in round iron pots, about 12 inches diameter and 16 to 18 inches high, along with 

 haematite iron ore crushed to powder ; these pots are packed in a furnace, and heat 

 is applied from 24 hours to several days ; the oxygen abstracts the carbon from the 

 metal of which the articles are made, and they become to a certain extent malleable, 

 so much so, that pieces a quarter of an inch thick may be bent almost double, and can 

 be drawn out under a hammer. Forks, table-knives, scissors, and many other cheap 

 articles are so made ; also a vast variety of parts of cotton and flax machinery are so 

 manufactured, especially those parts which are difficult to forge. 



' Damascxis ' or ' damasked steel ' is made by melting together iron and steel, or 

 bars of steel of high and low degrees of carbonisation ; it may also be produced by 

 melting hard and soft steel in separate crucibles, mixing them together whilst fluid, 

 and immediately pouring the mixture into an ingot mould ; the damask is shown by 

 the application of dilute acid to the surface when brightened. The analysis of a 

 genuine Damascus sword-blade has shown that it is not a homogeneous steel, but a 

 mixture of steel and iron. 



Bessemer's Steel. The undoubted success, and therefore the general adoption of 

 this process for converting iron into steel, which derives its name from its inventor, 

 renders it necessary that a full description of the process should be given. 



The facility which the blast-furnace affords, of at once separating from the ores 

 of iron the greater part of the extraneous matters which they contain, has rendered 

 its employment almost universal, as a preliminary process in the production of 

 malleable iron. 



The crude metal thus obtained, although separated from a large proportion of its 

 impurities, is nevertheless found to be intimately combined with carbon and silicum, 

 and generally with sulphur, phosphorus, manganese, and some other substances, in 

 comparatively minute quantities ; the decarbonisation of the iron, and the separation 

 of these substances, as far as is practicable, claims the first care of the manufacturer. 

 For this purpose the crude metal is either formed into pigs, which are afterwards 

 remelted in the ' finery furnace,' or it is run, while still in a fluid state, from the 

 blast-furnace direct into the finery fire, where it is subjected to the action of blasts of 

 air, directed downwards upon its surface, at a particular angle. The crude metal, 

 thus acted upon by the oxygen of the air, is in about three hours sufficiently de- 

 carbonised and refined, to render it suitable for the puddling process ; it is therefore 

 run out of the ' finery ' and formed into a large flat plate, which is of an extremely 

 hard and brittle character, and presents physically no approach whatever to the 

 malleable state.' The hard and brittle mass, thus formed, is easily broken by tlio 

 hammer into pieces of a size suitable for the puddling furnace, to which it is con- 

 veyed, in order to bo more completely decarbonised and rendered malleable. 



Iron on the verge of fusion loses its power of cohesion, and readily crumbles down 

 into a coarse powder. This property is common to pig and to refined iron, and advan- 

 tage is taken of it in the puddling process. The workman watches the temperature 

 and appearance of the metal, and seizing the proper moment, divides the masses of 

 refined iron into small fragments, which he spreads about the furnace, and finally 

 breaks it down into a kind of coarse sand. The metal, in this divided state, exposes a 

 large extent of surface to the refining action of the fluid cinder, as well as to the vo- 

 lume of air constantly passing through the furnace. By increasing the heat, the 

 granulated mass swells up and emits numerous jets of blue flame. At this point the 

 puddler diligently stirs and works the metal, until the flame appears of a whiter 

 colour, and the metal becomes clotty and tenacious, or as the workmen term it, ' comes 

 to nature ; ' after which, the iron is gathered into balls, and is then removed, as 

 quickly as possible, to the squeezer, where much of the fluid scoriae and other mechani- 

 cally mixed impurities aro driven out, leaving a mass or billet of iron, composed of 

 thousands of separate fragments of metal, the entire surface of every one of which is 

 more or less coated with dry oxide, or fluid silicate of the oxide of iron. The great 



