It has for many years been believed in England, that Swedish iron derives some of its valuable steel-making properties from the presence of a small quantity of manganese ; hence the question—might not manganese be profitably added to English iron l Mr. Heath took up the subject, spent a fortune upon It, greatly enriched Sheffield, and died broken-hearted. In 1839 he devised a mode of combining carbon with manganese, to produce a carburet, which converted English iron into very good steel. The manganese appeared to him to act as a sort of detergent, taking away certain impurities from the iron. Unfortunately for his interests, he improred the process; he put into the furnace the elements of the carburet (carbon and manganese) instead of the carbu ret itself, thereby lessening the expense. He neglected to obtain a second patent for this improvement; the Sheffield manufacturers saw the flaw, made the new steel without paying him any royalty and defied him. The suit of Heath es. Unwin, carried on for eleven years, in all the various forms known to English law and equity, ruined Mr. Heath, who died In 1850. His widow succeeded in obtaining a small interest arising out of the patent, but quite disproportionate to the importance of the invention. Mr. Webster has stated that, between 1839 and 1855, buyers of Sheffield cast-steel goods benefited to the extent of two millions sterling by the lowering of prices due to Mr. Heath's process.
Steel is of a lighter gray than iron. It is susceptible of receiving a very high polish, and this is greater as the grain is finer. When steel is hardened its volume is increased. When heated to redness, and slowly cooled, it is scarcely harder than iron ; but by very rapid cooling it becomes hard, and so brittle as to be readily broken. The fracture is usually fine grained. In ductility and malleability it is much infe rior to iron, but exceeds it greatly in elasticity and sonorousness. It may be subjected to a full red heat, or 2786° Fehr., without melting, and is therefore less' fusible than cast-iron, but much more so than wrought-iron. Pieces of steel which have not been cast may be readily welded together or with iron ; but after casting, the operation is more difficult. In order to give to steel the different degrees of hardness required for various purposes to which it is applied, it is subjected to the process of tempering. The higher the temperature to which it is raised, and the more sudden the cooling, the greater is the hardness. Thus when immersed in mercury the hardness is greatest, on account of the good conducting power of the metal, and its consequent ready abstraction of heat. After this comes acidulated water, salt water, common water, and lastly oily or fatty bodies. It is found that, according to the degree to which steel is tempered, it assumes various colours, and formerly these colours served as guides to the workman ; now, however, a thermometer, with a bath of mercury or of oil, is employed, and the operation is performed with a much greater degree of certainty. Into this bath the articles to be tempered are put, with
the bulb of the thermometer graduated up to the boiling-point of mercury. The tempering heat varies from 430° Fahr. (for lancets) to 600' (for pit saws).
Paddled and Bessemer Steel.—Arising out of the inquiries concerniug the relations between iron and steel, several new modes of making steel have recently been introduced or proposed. Hitherto, most English steel has been made by the concerting process, already described ; but on the Continent it is more usual to adopt what is called the raw method, puddling the metal in a charcoal furnace. The English method raises the amount of carbon in or with bar-iron up to about I per cent.; the Continental method lowers the amount of carbon in or with pig-iron from 4 to 1 per cent. Riepe's method, patented in 1850, and worked some time by the Low Moor Iron Company and the Mersey Steel Company, is for making a kind of steely iron by the puddling process, good enough for most COMM= purposes—hard and unyielding, or soft and silky, according to the extent to which the process is carried. To produce this steel, pig-iron is thrown into a puddling-furnace [FustNees ; IRON MANUFACTURE), together with a little iron slag, salt, clay, and oxide of manganese ; the molten metal is worked or puddled beneath the scum, and is worked up into balls or blooms at a certain stage. Captain Uchatius, engineer of the Imperial Arsenal at Vienna, has devised a method of making steel in which (as ho thinks) English iron would suit as well as Swedish or Russian. He brings the iron to a granular state, by running it from a furnace into agitated cold water. These grains are mixed with some cheap oxygen-yielding material, such as spathose iron-ore, put into a crucible, and melted in a east-steel furnace. The pig-iron gives up some of its carbon and its earthy impurities to the oxygen, and becomes steel. The smaller the granules, the softer the steel. Uchatius produces 25 lbs. of steel from 24 lbs. of granulated iron, 4 lbs. of spathose ore, 4 lbs. of oxide of manganese, and a little clay. Sir F. Knowles has introduced a method in which a retort instead of a crucible is used; while the crude' Iron is mixed with hot gases rich in carbon. The processes of Uchatius and Knowles seem better adapted for the laboratory than for large manufacturing operations. Other modes of producing steel directly from the crude iron have been 'introduced, with varying success, by Clay, Saunderson, Plant, Nasmyth, Mortier, and others.