Data on ultra-violet solar radiation and the solarization of window materials

Abstract

In this paper the following topics are discussed: 1. The variation of ultraviolet solar radiation, available for therapeutic purposes, as dependent upon the time of the day, the season of the year, the altitude and geographic latitude of the station, the pollution of the atmosphere by smoke, etc. gfcfr* 1*2 ] Transparency of Window Materials 631 Coblentzl Stair Transparency of Window Materials 633 antirachitic potency. Since, as will be noticed presently, in the wintertime the short wavelength limit of solar radiation is about 305 m/x, it appears that the spectral range of ultraviolet solar radiation, useful for therapeutic purposes in preventing rickets, is only about 5 to 10 m/x in width.

Evaluation of ultraviolet solar radiation of short wave lengths

“…The earliest investigations [1,2], using a thermocouple and filters of window glass, led to an estimate of the upper limit in intensities that might be expected in ultraviolet solar radiation, useful for therapeutic purposes.…”

An Alkaline Solution of Potassium Chromate as a Transmittancy Standard in the Ultraviolet*

“…Not only do all but a few special glasses absorb completely below 290 m/x, but, in addition, the ultraviolet spectral transmittances of many glasses change on exposure to strong ultraviolet radiant flux [2, 3,4]. In these respects solutions in cells with quartz end plates are found to be superior to glasses for use in the ultraviolet.…”

“…[5, p. 200] lists potassium chromate, azobenzene, and potassium nitrate as solutions that can be accurately prepared as standards for the calibration of spectrophotometers. 3 Photoelectric Spectrophotometry Group of England has recently conducted a collaborative test on the use of K2Cr207 [6]. 4 Solutions can, of course, also be used in the visible region.…”

Permanence of glass standards of spectral transmittance

“…It is possible, of course, that the cobalt blue glas might solarize at shorter wavelength. Those interested in this effect hould r ead the papers by Coblentz and tair, who m ade an exten ive study of the ultraviolet solarization of window glasse and other materials (10,11] .…”