ANTIRACHITIC VALUE OF THE SUN'S RAYS THROUGH VARIOUS SPECIAL WINDOW CLASSES

Abstract

At least three special glasses are on the market at present, which, according to the claims of the manufacturers, will transmit the antirachitic rays of sunshine. These glasses are: (1) Vitaglass—manufactured in England and marketed in the United States by the Vitaglass Corporation, New York; (2) Vioray glass—marketed in Canada by W. E. Phillips Company, Oshawa, Ontario, and (3) Corning special glass—manufactured by the Corning Glass Works, Corning, N. Y. Vioray and Corning glass have been available for only a short time. In February, 1927, we reported that "Rays from December sunlight which had passed through Vitaglass had an antirachitic effect which was roughly one-fourth the value of the direct rays. Rays which had passed through ordinary glass had no antirachitic effect."¹Subsequently, in a report on window substitutes approved by the Council on Physical Therapy of the American Medical Association,²it was shown that the sun's rays