393 METALLURGY 



titanium as a "cleansing" addition which removes oxygen, nitrogen and other impurities, 

 rather than as an actual alloying element. The value of titanium was first established 

 in the case of rails, but its use has since extended to other classes of steel. As regards alloy 

 steels proper, the use of nickel, nickel-chrome and chrome-vanadium steels has extended, 

 chiefly through the growth of the automobile industry. The use of manganese steel and of 

 nickel steel rails has also been tried. 



The question of the corrosion of iron and steel has continued to receive much attention ; 

 apart from the general controversy between the "electrolytic" and the chemical (carbonic 

 acid) theories of corrosion, the electrolytic theory has received a serious check from the 

 researches of Heyn, who has shown that while the existence of local cells determines the 

 rapidity with which corrosion commences, it does not affect the ultimate rate of corrosion. 

 In America a new material, known under the name of American ingot iron or "open-hearth 

 iron," has been produced for the purpose of resisting corrosion; it is claimed that this metal 

 is the nearest practical approach to chemically pure iron and that it resists corrosion better 

 than mild steel. The material, however, has an appreciable content of copper it is even 

 suggested that copper is intentionally added to it, and that its non-corrodibility is due to 

 the copper. The addition of copper to steel for this purpose has also been introduced. 

 Some progress has also been made in the production of actually acid-resisting varieties of 

 cast-iron, such as the high silicon iron of Jouve and the material known as "tant-iron." 

 The use of approximately pure silicon metal for this purpose is also contemplated. 



The subject of the cementation of iron and steel has received much attention, the most 

 notable advances being probably those made by Giollitti and his collaborators at Turin: 

 by the use of charcoal and a mixture of carbon dioxide and x carbon-monoxide gases under 

 pressure in a furnace where both temperature and pressure can be varied, these workers 

 obtain a wide power of regulating both the intensity and depth of cementation and also the 

 width of the transition zone between carburised and non-carburised material. 



Copper (E. B. vii, 102 et seq.). The most marked feature in the metallurgy of 

 copper during the past three years has been the great development of basic converting, 

 causing a radical change in equipment, durability and tonnage *>f converters and in 

 general practice. Even standard shells of the older type have been re-lined with basic 

 material. Apart from this feature, progress has also been made in the handling of 

 ores; as regards transport, troughed conveyor belting has proved eminently successful 

 as compared with the electric car even for distances of four miles. The use of fine ores, 

 flue-dust etc. has also been advanced, so that ores for the blast-furnaces are now general- 

 ly screened so that the coarse charge can be worked at a higher rate. One interesting 

 development is that of blowing fine material into the converter through the twyers by 

 means of a jet of air at higher pressure than the blast. In the treatment of metallic 

 copper itself, the use of boron sub-oxide has been introduced. Boric anhydride is re- 

 duced by metallic magnesium, yielding magnesium borate, and boron sub-oxide. The 

 latter acts as a very satisfactory reducing agent on the copper and for castings intended 

 for electrical purposes removes oxygen so well that conductivities up to 97.5 per cent 

 have been obtained. The use of the boron sub-oxide to replace " poling " has also been 

 tried, but although the results are satisfactory there are practical difficulties on the 

 ground of expense and attack on the furnaces. 



Among the alloys of copper, Monel metal : a natural alloy of copper and nickel has 

 received extended use owing to the remarkable combination of strength with resistance to 

 corrosion which it presents. It has been used for screw propellers in battleships (U.S.S. 

 "Dakota") and for roofing large buildings (Pennsylvania terminal in New York). A 

 remarkable test at 1000 F. has shown the alloy to retain 80 per cent of its normal strength. 

 The alloys of copper with aluminium and manganese have also been studied very closely 

 (Ninth Report, Alloys Research Committee) ; one of these attains, in the form of rolled and 

 drawn rod, a tensile strength of 52 tons per sq. in. with 10 per cent elongation on two inches. 

 These alloys are remarkable for their resistance to corrosion and to abrasion. Another special 

 "bronze" is that of " Rubel," which contains 58 per cent of copper, 41 per cent zinc, and I 

 per cent chromium, and possesses remarkable mechanical properties. 



Aluminium (E. B. i, 767 et seq.). The production of this metal has increased and 

 a steady improvement in quality is being obtained; when the metal is excessively pure, 

 however, difficulties arise in working it. Its uses have developed considerably, prin- 

 cipally in the direction of cooking utensils and of large tanks for breweries and similar 

 purposes. The latter development has been facilitated by the established success of 

 methods of joining aluminium sheets by autogenous welding. Extruded aluminium 

 shapes, as well as the sheet metal, are also extensively used in carriage construction. 



