Science: Pre-Shrunk

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Shirts which are shrunk at the factory and therefore hold their own in the laundry are deemed by many a grateful tender-neck to be marvels of modern science.

Last week Corning Glass Works of Corning, N. Y. announced a newer marvel which some day soon will make house wives grateful: preshrunk glass. A goblet made of this glass is so dense and tough (i. e., so resistant to expansion and con traction) that it can be heated cherry-red, then dipped in iee water without breaking.

Researchers at Corning put a dish of preshrunk glass on a cake of ice, then poured molten iron into the dish. It did not crack.

Shrunk glass is made by mixing two borosilicate formulas, one of which is soluble in acid, the other not. The mixture is melted and the glass is molded or blown to the desired shape. Then it is soaked in dilute nitric acid, which eats away the soluble ingredients, leaving the glass honeycombed with air spaces. Again heat is applied and the glass becomes solid, shrinking 35% in volume.

Corning officials figured that it would take two more years to manufacture and market the new glass in quantity. Then, they predict, it will be used in industry and in households wherever heat-resistant glass is needed. Expansion of the new glass under heat is imperceptible — three times less than the expansion of the great 200-inch telescope mirror which Corning cast for Caltech. When the next big piece of astronomical glass is made, preshrunk glass will probably be used.