toughness, but the mix was not homogeneous and the results of the experiment were not considered to be reliable. "and no one understood that the real reason why the iron mined in Noricum produced such superb steel lay in the fact that it contained a small amount of manganese uncontaminated by phosphorus, arsenic, or sulphur, and so was the raw material of manganese steel." In 1860, Sir Henry Bessemer, trying to perfect his Bessemer process of steel making, found that adding spiegeleisen to the steel after it was blown helped to remove excess sulfur and oxygen. Sulfur combines with iron to form a sulfide that has a lower melting point than steel, causing weak spots, which prevented hot rolling. Manganese is usually added to most modern steels in small amounts because of its powerful ability to remove impurities. Hadfield was in search of a steel that could be used for the casting of tram wheels which would exhibit both hardness and toughness, since ordinary carbon steels do not combine those properties. Steel can be hardened by rapid cooling, but loses its toughness, becoming brittle. Steel castings can not usually be cooled rapidly, for irregular shapes can warp or crack. Mangalloy proved to be extremely suitable for casting, as it did not form gas pockets called "blow-holes", and did not display the extreme brittleness of other castings. Hadfield had been studying the results of others who experimented with mixing various elements with steel, such as Benjamin Huntsman and A.H. Allen. At the time the manufacture of steel was an art rather than a science, produced by skilled craftsmen who were often very secretive. Thus, no metallurgical data about steel existed before 1860, so information about the various alloys was sporadic and often unreliable. Hadfield became interested in the addition of manganese and silicon. The Terre Noire Company had created an alloy called "ferro-manganese", containing up to 80% manganese. Hadfield began by mixing ferro-manganese with crucible steel and silicon, producing an alloy of 7.45% manganese, but the material was unsatisfactory for his purposes. In his next attempt, he left out the silicon and added more ferro-manganese to the mix, achieving an alloy with 1.35% carbon and 13.76% manganese. Upon creating mangalloy, Hadfield tested the material, thinking that the results must have been erroneous. It looked dull and soft, with a submetallic luster similar in appearance to lead, yet sheared the teeth off