A new and profitable field was opened for the use of electricity by the invention of the electric furnace. Sir Humphry Davy produced his electric arc in 1808 and was greatly impressed with its fusing properties. He melted many metals with the arc and found that it fused platinum just as easily as an ordinary tallow candle melts beeswax. The electric furnace, which is now extensively used in chemical and metallurgical works, is simply a large electric arc provided with means for containing the heat. Furnaces lined with carbon are now heated to over 4,000 degrees centigrade. 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.