It may not perhaps be considered remark able that manganese, a non-magnetic metal, should destroy the magnetic qualities of iron when alloyed with it to the extent of 12 or 13 per cent, but surely it is quite unexpected to find a nickel steel, of 25 per cent Ni, almost non-magnetic, since iron, nickel and cobalt are the only strongly magnetic metals. Non-mag netic alloys of magnetic metals while hardly to be expected are not more remarkable than the magnetic alloys of Heussler, made of non magnetic metals and containing no iron, nickel or cobalt. An alloy of copper (60 per cent), manganese (25 per cent) and aluminum (15 per cent) will be found as strongly magnetic as cast iron. While steels of 10 to 15 per cent nickel are brittle and manganese steels of 3 to 8 per cent manganese exhibit the same prop erty in a greater degree, a combination of nickel and manganese in the proportions of 15 and 6 gave Hadfield his alloy, cele brated for its toughness. A two and one-half inch cast bar of this alloy has been bent double cold. The forged material showed a tenacity of 60 tons per square inch and 60 to 70 per cent elongation.
Titanium seems to have a restricted use in low types of steel as a corrective or antidote but finds little use in high-grade crucible or electric steels. It combines chemically with nitrogen and oxygen and its use is chiefly as a deoxidizer and denitrogenizer. The chief field for titanium has been found in rail-steel manufacture, and less segregation and stronger and tougher and harder rails are said to re suit from its use. Comstock and Corse have done most of the recent work on this element.
Uranium is one of the newer elements being worked with. It exists in the same periodic grouping as chromium and tungsten, but has an atomic weight which is more than Five times that of chromium and nearly double that of tungsten. At the present time, quite extensive experiments as an addition to high-speed steels are being carried on, but without much prom ise of success. It oxidizes readily and the oxide is so heavy that it does not free itself from the molten steel but produces a dirty steel Cobalt also like uranium is in the experi mental stage. Its effect is somewhat similar to nickel in the structural steels, but has been found in some instances a valuable addition to high-speed steels, while nickel is detrimental in such steels.
Molybdenum steels were one of the first steps in the evolution of high-speed steels, but they are not as good as the tungsten steels and have been generally abandoned, although molybdenum air-hardening steels, high in car bon, are still used. Molybdenum exerts a very beneficial effect on the magnetic qualities. Some
of the best permanent magnet steels studied by Mme. Curie and by the writer were alloys of this element.
Molybdenum alloys with chromium and nickel are used to some extent in the manu facture of guns, armor plates, steel helmets, airplane cranks, etc.
Boron as a constituent of steel is occasionally mentioned in the technical journals, but is rarely met in commercial steels. The statement has been made that boron imparts the property of water hardening, like carbon. Charpy and Mois san deny that boron causes hardening in the ordinary sense; it does raise the tensile strength when quenched.
Bibliography.— Guillet,