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Felspar supply of the United States
Mar., 1915.]
CURRENT TOPICS.
379
Felspar Supply of the United States. A. S. WATTS. (Trans. Amer. Ceram. Soc., xvi, 8o.)mThe demand for pure felspar being greater than European sources can supply, the author recounts the location and extent of felspar deposits (apparently pegmatite) in the United States east of the Mississippi River. The influence of the methods of mining and grinding upon the quality of the finished product is shown by the good reputation of Maine felspars, which are not naturally very pure on account of a quartz content which cannot be eliminated. Analyses given of American spars show variations in alkali content from 8 to 16 per cent. The chief States concerned are Maine, Connecticut, New York, and Pennsylvania. In the lastnamed the largest deposit of soda felspar in the world was found, but is almost exhausted. Maryland is expected to supply soda felspar in the future; the soda pegmatites contain 6 per cent. Na20 and 4 per cent. K oO. In Virginia and North Carolina felspar has been subsidiary to mica mining hitherto. In Georgia the production of felspar has not yet been attempted. Coal Consumption of New York's Generating Stations. ANON. (Electr. World, lxiv, No. 14, 66o.)--The average consumption of fuel in all the central stations of New York City is at the rate of 3.3 pounds per kilowatt-hour, inclusive of all standby and other losses. The average consumption of fuel by insolated plants is at the rate of not less than IO pounds of coal per kilowatt-hour, or three times the average rate of central-station operation, according to a committee of the Association of Edison Illuminating Companies. Compared with insolated plants, central-station generation of electricity is conserving in New York City alone about 1,75o,ooo tons of fuel a year by superior economy in production. Measurement of Air Velocities, Pressures and Volumes. W. CRA.~n'. (Manchester Lit. and Phil. Soc. Mere., lviii, 7, I . ) - - F o r various reasons the anemometer is unsatisfactory in measuring air velocities; it is rather an indicator. The Pitot tube is accurate, provided the facing tube is small and of such a form that stream-line flow is not much disturbed. Various tubes are compared; the Nipher collector is very inaccurate, and the Brab~e tube seems superior to anything but the Standard Pitot with static tube in pipe wall. This latter involves holes with good internal surfaces to be drilled at various points, and is often impossible in commercial work. The Brab6e tube seems very little affected by faulty setting. In determining the volume of air passing through a pipe, the author takes the central velocity x as a coefficient to give the mean velocity. For central velocities of 6.89, 7.72 , 8.53 , 9.16, and 9.42 metres per second, the coefficient is 0.8, 0.9, 0.9, 0.9, and 0.88 respectively. With water flow the author remarks that the coefficient is about 0.85. The KrellPrandtl pneumometer is also described.
CURRENT TOPICS.
379
Felspar Supply of the United States. A. S. WATTS. (Trans. Amer. Ceram. Soc., xvi, 8o.)mThe demand for pure felspar being greater than European sources can supply, the author recounts the location and extent of felspar deposits (apparently pegmatite) in the United States east of the Mississippi River. The influence of the methods of mining and grinding upon the quality of the finished product is shown by the good reputation of Maine felspars, which are not naturally very pure on account of a quartz content which cannot be eliminated. Analyses given of American spars show variations in alkali content from 8 to 16 per cent. The chief States concerned are Maine, Connecticut, New York, and Pennsylvania. In the lastnamed the largest deposit of soda felspar in the world was found, but is almost exhausted. Maryland is expected to supply soda felspar in the future; the soda pegmatites contain 6 per cent. Na20 and 4 per cent. K oO. In Virginia and North Carolina felspar has been subsidiary to mica mining hitherto. In Georgia the production of felspar has not yet been attempted. Coal Consumption of New York's Generating Stations. ANON. (Electr. World, lxiv, No. 14, 66o.)--The average consumption of fuel in all the central stations of New York City is at the rate of 3.3 pounds per kilowatt-hour, inclusive of all standby and other losses. The average consumption of fuel by insolated plants is at the rate of not less than IO pounds of coal per kilowatt-hour, or three times the average rate of central-station operation, according to a committee of the Association of Edison Illuminating Companies. Compared with insolated plants, central-station generation of electricity is conserving in New York City alone about 1,75o,ooo tons of fuel a year by superior economy in production. Measurement of Air Velocities, Pressures and Volumes. W. CRA.~n'. (Manchester Lit. and Phil. Soc. Mere., lviii, 7, I . ) - - F o r various reasons the anemometer is unsatisfactory in measuring air velocities; it is rather an indicator. The Pitot tube is accurate, provided the facing tube is small and of such a form that stream-line flow is not much disturbed. Various tubes are compared; the Nipher collector is very inaccurate, and the Brab~e tube seems superior to anything but the Standard Pitot with static tube in pipe wall. This latter involves holes with good internal surfaces to be drilled at various points, and is often impossible in commercial work. The Brab6e tube seems very little affected by faulty setting. In determining the volume of air passing through a pipe, the author takes the central velocity x as a coefficient to give the mean velocity. For central velocities of 6.89, 7.72 , 8.53 , 9.16, and 9.42 metres per second, the coefficient is 0.8, 0.9, 0.9, 0.9, and 0.88 respectively. With water flow the author remarks that the coefficient is about 0.85. The KrellPrandtl pneumometer is also described.