Ke Alakai o Hawaii, Volume VI, Number 30, 23 November 1933 — Pictures Made by Invisible Black Light [ARTICLE]

Pictures Made by Invisible Black Light

Popular Mechanics Some classes of photographs ean be taksn in darkness without' the aid of viāble lig£it by uslng an ultraviolet lamp eonstructed with a bulb of black glass whieh filters out nearly all the visible rays and permits only the of long-wave ultraviolet beams. These rays are strong in actinic Quality, that property of radiant energy whieh produces the ehemieāl changes on photographlc plates.