Science: Ultra-Violet Glass

To find the real value of ultraviolet glass and glass substitutes Dr. Janet Howell Clark, 39, associate professor of physiology at Johns Hopkins School of Hygiene & Public Health, measured light all last March, April and May. The discoveries, published last fortnight, were surprising:

The best ultraviolet glass, when a little old, lets only one third of the available ultraviolet sun rays pass through. (Manufacturers claim no more.)

The average amount of ultraviolet light in a 32-ft. room glazed with ultraviolet glass is only 1/600th of the noon-day's sun.

A person in such a...

Want the full story?

Subscribe Now


Learn more about the benefits of being a TIME subscriber

If you are already a subscriber sign up — registration is free!