Science: Salt; Cotton

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In New York, Michigan, Vermont, Maryland, Indiana, Louisiana, Mississippi, Ohio, Kansas and Pennsylvania lately some 100 miles of experimental clay and gravel roads treated with rock salt (ice-cream freezer kind) have been laid. After several months' use by fairly heavy traffic the salted roads are standing up admirably, Arthur D. Little, Inc.'s Industrial Bulletin reported last week, and one stretch near Ithaca, N. Y. came through a pounding by nine inches of rain without visible effect. Developed by Cloyd Delson Looker, research director of International Salt Co., and Heinrich Ries, Cornell University geologist, the treatment makes clay hard like concrete, retards evaporation so that the surface remains moist and firm, provides an almost nonskid track. The cost per mile ($1,200) is about a third that of asphalt, one-twentieth that of concrete.

Another highway material currently attracting attention is cotton. In Mississippi last month huge bolts of open-mesh cotton fabric were unrolled, like a mile-long rug, on the new road between Greenville and Scott, under the eyes of 400 engineers, farmers and Federal bureaucrats, including Manager Oscar Johnston of AAA's Cotton Pool. The cotton, fixed by tar. is laid between the clay and gravel base and the asphalt surfacing. It acts as a binder, prevents stretching and cracking. Extra cost of the binder is $750 per mile, which, experiments in other States show, should be returned later by decreased maintenance bills. Cotton men believe that when highway commissions get over their scepticism 2,000,000 miles of secondary (''farm-to-market") roads will be found suited to cotton treatment, consuming 13,000,000 bales.