1959 Press Photo General Electric Quartzline Lamps Stop Incandescent Blackening

Experimental 500-watt lamps at top contained no iodine. They darkened noticeably after only two hours burning. Those at bottom used a revolutionary iodine cycle action and are still clean after 1,000 hours of burning. This iodine cycle keeps the tubular quartz lighting lamps free from filming by evaporating particles of the tungsten filament.

Photo is dated 1959.

Photo measures 10.25 x 7.75 inches.