When the electrical manufacture of aluminum on a large scale was started at Niagara, Dr. Edward Acheson, who was impressed by the industrial needs of cheap abrasives, accidentally discovered that by heating a piece of porcelain to a high temperature in an electric furnace and bringing it in contact with pure carbon, the carbon was rendered very hard. In 1891 he carried on experiments with high currents and a mixture of ground coke and sand. He found a method of fusing these so that the oxygen of the sand passed off with carbon in the form of carbonic acid gas, and the reduced metallic silicon combined with an equal atomic weight of carbon and produced a new body which he named carborundum. The success met with in making carborundum led to the devising of a method of manufacturing artificial graphite in the electric furnace. A soft, non-coalescing graphite was made in 1906. This is extensively used in lubricating heavy machinery.
Dr. Acheson produced the first chemically pure artificial carbon in his electric furnace in 1911. By using pressure during consolidation this carbon may eventually be converted into diamonds.
Another valuable product of the electric furnace, acetylene gas, was discovered in Dublin by Edmund Davy in 1836. Subsequently numerous chemists discovered means for making carbides. T. Sterry Hunt, an American chemist, observed in 1886 that oxides of the alkaline metals and of calcium, magnesium, aluminum, silicon, and boron could be reduced in the electric furnace in the presence of carbon and could be alloyed with other metals. He also found that silicon and acetylene could be made that way.
T. L. Wilson, a Canadian engineer, in attempting to make aluminum bronze in an electric furnace, devised an experiment for reducing lime with carbon. He found that this produced calcium carbide and secured a patent for the invention in 1892. Variations of this process are now used for manufacturing nitrogen and nitrates from atmospheric nitrogen.
Wireless developments have resulted from the work of many separate investigators. K. A. Steenheil in 1838 used the earth return in live telegraphy and suggested the possibility of wireless telegraphy. Joseph Henry produced the first high-frequency oscillations in America in 1840. Lord Kelvin in 1853 enunciated the mathematical principles governing uncoupled electrical oscillatory circuits. Joseph Heyworth patented a wireless telegraphic process in 1862. Clark Maxwell in 1867 predicted the existence of electromagnetic radiations and these were demonstrated by Hertz in 1887. Hughes discovered the phenomena of the coherer and Branby used Hughes's coherer for wireless wave detection in 1892. A. E. Dolbear secured United States patents for a system of wireless telegraphy using aerials in 1886. Sir Oliver Lodge described his wireless system before the Royal Society in 1894 and in the same year Popoff issued descriptions of his wireless system.
Wireless telegraphy became commercially practicable in 1897 when G. Marconi secured the promotion of the Wireless Telegraph and Signal Company in England. Marconi succeeded in turning to commercial account a long series of brilliant discoveries in electricity, and this success has led to numerous kindred discoveries. De Forest's three-electrode thermionic detector, known as an Audion, invented in 1907 and improved in 1911 by Lieben and Reiss, in 1913 by Meisser and in 1914 by Langmuir, opened up great possibilities for sound transmission by wireless telephony.
The electric deposition and refining of metals have been referred to in previous chapters. Many industries are based upon these. Niepce produced commercially successful photographs in 1838. Earlier, in 1824, he had etched plates for printing and in that year published his photo-engraving of Cardinal d'Amboise. Fox Talbot patented a mixture of gelatine and bichromate of potash to take the place of the bitumen used by Niepce as a plate coating. Gillot found in 1872 that Fox Talbot's method of making intaglio plates could also be used for making relief blocks. In 1885-1886, F. E. Ives sealed two single-line screws together and made a new fine cross-line screen, which resulted in the development of the half-tone process. Ives at this time also developed the three-color photo-engraving process.
Photography and photo-engraving are so widely used and are so intimately connected with our civilization that few people now realize that the great industries based upon them are the results of a few scientific discoveries of a couple of American and European scientists made only a generation or two ago.
