In the _making_ of _shot_, the old method was to pour the melted metal through a sieve, and allow it to drop from a tower 180 feet or more in height. David Smith’s patent, No. 6,460, May 22, 1849, provided an ascending current of air through which the metal dropped, and which, by cooling the shot by retarding its fall and bringing a greater number of air particles in contact with them, avoided the necessity of such high towers. In 1868, Glasgow and Wood patented a process of dropping the shot through a column of glycerine or oil. Still another method is to allow the melted metal to fall on a revolving disk, which divides it into drops by centrifugal action. _Alloys._--Over 300 United States patents have been granted for various alloys of metals. The so-called _babbit metal_ was patented in the United States by Isaac Babbit, July 17, 1839, and in England, May 15, 1843, No. 9,724. This consists of an antifriction compound of tin, 10 parts, copper, 1 part, and antimony, 1 part, and is specially adapted for the lubricated bearings of machinery. _Phosphor bronze_, introduced in 1871, combines 80 to 92 parts copper, 7 of tin, and 1 of phosphorus (see United States patents to Lavroff, No. 118,372, August 22, 1871, and Levi and Kunzel, No. 115,220, May 23, 1871). The addition of phosphorus promotes the fluidity of the metal and makes very clean, fine and strong castings. In alloys of iron, _chromium steel_ is covered by patents to Baur, No. 49,495, August 22, 1865; No. 99,624, February 8, 1870, and No. 123,443, February 6, 1872; _manganese steel_, by Hadfield’s patent, No. 303,150, August 5, 1884; _aluminum steel_, by Wittenström’s patent, No. 333,373, December 29, 1885, and _phosphorus steel_, by Kunkel’s patent, No. 182,371, September 19, 1876. The most recent and perhaps most important, however, is _nickel steel_, used in making armor for battleships. This is covered by Schneider’s patents, Nos. 415,655, and 415,657, November 19, 1889. In 1878 England led the world in the iron industry with a production of 6,381,051 tons of pig iron, as compared with 2,301,215 tons by the United States. In 1897 the United States leads the world in the following ratios: Tons Pig Iron. Tons Steel. United States 9,652,680 7,156,957 Great Britain 8,789,455 4,585,961 Germany 6,879,541 4,796,226 France 2,472,143 1,312,000 The United States made in that year 29.30 per cent. of the world’s production of pig iron, and 34.58 per cent. of its steel. The total output of the whole world in that year was 32,937,490 tons pig iron, and 20,696,787 tons of steel.