Show I New Optical Glass A new German optical glass Is designed de do- signed for colorless spectacles spectacles spectacles-in- in instead stead stend of ot the time usual usua colored ones ones to to give protection against violet ultra-violet ra rays s such as ns give trouble in climbing high mountains or working In the light of ot the time quartz mercury lamp Time The glass Is due hue to the discovery that a suitable mixture of rare earths In glass flux absorbs ab nb absorbs sorbs the harmful rays ras Such earths as ns neodymium erbium cerium and thorium may be used In varying combinations und and the protective protective protective tive glass shows objects and landscapes land stapes in natural colors u ft s 4 |