STEEL 



903 



pressure exerted by the squeezer suffices to so fur remove the fluid coating of con- 

 tiguous particles as to bring their surfaces into actual contact, and consequently to 

 effect an union at such parts. 



In the puddling process, the granules of metal gradually pass from the state of 

 brittle finery-iron to steel, and passing that point, through every gradation of hard, 

 medium, and soft steel, eventually arrive at the softest stage of decarbonised iron. 

 The time occupied in these changes varies with the size of the granules, their 

 temperature, and the extent to which each is exposed to the action of the air passing 

 through the furnace. 



It need not be a matter of surprise that when it was first proposed, by Mr. Bessemer, 

 to convert crude pig-iron into malleable iron, while in a fluid state, and to retain the 

 fluidity of the metal for a sufficient time to admit of its being cast into moulds, with- 

 out the employment of any fuel in the process, that his proposition was almost 

 generally looked upon as a mere day-dream, which the practical man felt bound to 

 disbelieve. 



Chemical investigation soon pointed out the real source of the difficulties which 

 surrounded the Bessemer process. It was found that, although the metal could bo 

 wholly decarbonised, and the silicium be removed, the quantity of sulphur and phos- 

 phorus was but little affected. As different samples were carefully analysed, it was 

 ascertained that the red shortness was always produced by sulphur, when present to 

 the extent of one-tenth per cent., and that cold shortness resulted from the presence 

 of a like quantity of phosphorus. It therefore became necessary to remove these 

 substances. Steam and pure hydrogen gas were tried, with more or less success, in 

 the removal of sulphur, and various fluxes, composed chiefly of silicates of the oxides 

 of iron and manganese, were brought in contact with the fluid metal during the pro- 

 cess, and the quantity of phosphorus was thereby reduced. 



In manufacturing tool-steel of the highest quality, it was found preferable, for 

 several reasons, to use the best Swedish pig-iron, and when converted into steel, by 

 the Bessemer process, to pour the fluid steel into water, and afterwards to remelt the 



1908 



shotted metal in a crucible, as is at present practised with blister steel, by which 

 system the small ingots required for this particular article are more perfectly and 

 more readily made. The production of first-class steel by the new process, although 

 a mater of deep interest in one of the smaller branches of the iron trade, still left 

 untouched that great source cf this country's prosperity, the manufacture of malleable 

 iron. It was, therefore, impossible to rest content without accomplishing this, the 

 original object of the invention. On examining into the stores of mineral wealth so 

 abundant in these islands, it was found that iron ore of the requisite purity existed 

 as red haematite in vast beds. There are also extensive veins of spathoso ore or car- 

 bonate of iron, and magnetic ores. 



4 The form of converting vessel which has been found most convenient, and by which 

 superior specimens are produced, is shown in ./?</. 1908. The vessel is mounted oa 



