The usual catalyst is platinum gauze (8o to 150 mesh per in., wire diameter o•ooi to 0.003 in.), four layers being frequently employed. A pre-heated mixture of ammonia and air is blown through the catalyst; the time of contact with the platinum is 0.0001 sec. and the temperature i,000° C; the speed is important. With good conditions the reaction, can be realized to the extent of about 95%. If all the ammonia is not oxidized it subsequently reacts with the oxides of nitrogen. It is reported that a granular iron oxide mixed with other oxide promoters has been used successfully in place of platinum. The oxidation of the nitric oxide and recovery as nitrates and nitrites follows, as previously described.
BIBLIOGRAPHY.—Physical and Chemical Data of Nitrogen Fixation, and Report of the Nitrogen Products Committee (Stationery Office, London, 1918 and 1919 resp.) J. R. Partington and L. H. Parker, The Nitrogen Industry (1922), contains many illustrations; Report on the Fixation and Utilization of Nitrogen (Washington, 1922) contains flow-sheet diagrams and bibliography to 1922 ; B. Waeser, Die Luft stickstoffindustrie (Leipzig, 1922), trans. by E. Fyleman and J. and A. Churchill, as The Atmospheric Nitrogen Industry (1926) with appen dices to bring the information up-to-date; J. R. Partington, "Nitrogen Fixation" in Thorpe's Dictionary of Applied Chemistry; articles in Ull mann's Encyklopaedie der technischen Chemie ; Badische Anilin- and Scda-Fabrik (published by the firm, 1925). (J. T. H.) While the industrial fixation of atmospheric nitrogen had its birth in the United States when the Atmospheric Products Com pany was organized at Niagara Falls, N.Y., to exploit the Bradley and Lovejoy patents, little nitrogen was fixed in the United States until after the World War. A Pauling furnace was operated at Nitrolee, S.C., from 1913 to 1916. Another plant was operated by the arc process at Le Grande, Wash., for ten years. The exces
sive cost of electric energy, however, made it impossible for these plants to compete with the synthetic ammonia plants. The Ameri can Cyanamid Company began the operation of the process, for which it is named, in 1907, and has increased its capacity from time to time. The U.S. Nitrate Plant No. 2 at Muscle Shoals, Ala., was also erected to operate the cyanamide process, but has never produced commercially. ("Muscle" is the common spelling, of "mussel" in the Colonial period.) The first attempt in the United States to synthesize ammonia directly was at U.S. Nitrate Plant No. 1, Sheffield, Ala., but this was an experimental plant, the continuous operation of which was never realized. Following the war the Atmospheric Nitrogen Corporation began operations at Syracuse, N.Y., reaching in 1927 an annual capacity of 11,550 tons. A number of small plants fol lowed, using for the most part by-product hydrogen. These were soon followed by a plant at Seattle, Wash., using electro lytic hydrogen, and Lazote, Inc., at Charleston, W. Va., employ ing water-gas hydrogen, with a production capacity of 6,35o tons in 1927. In 1928, at Hopewell, Va., the first unit of a plant of some 30,00o tons capacity began the manufacture of syn thetic sodium nitrate, having the distinction of being the first plant to produce directly a synthetic material identical with Chilean nitrate. Synthetic ammonia processes operating in the United States are for the most part modifications of the Haber, Casale and Claude processes. However, there has been developed a modification so extensive as to entitle it to be known as an "American Process." This has proved such an efficient method for fixing atmospheric nitrogen as to be installed in the newer plants erected both at home and abroad. (H. E. H.)