National Geographic : 1943 Jan
The National Geographic Magazine Making Glass Begins with "Mining" Sandstone in an Open-face Quarry A vast sandstone ledge near Berkeley Springs, West Virginia, has 99.8 percent pure silica, and also a low content of iron, enemy of transparency in glass making. Stone is reduced to original quartz grains which are then mechanically "scrubbed" under water, and graded over electric vibrating screens. The Pennsylvania Glass Sand Corporation ships sand to glass plants in paper-lined boxcars. Yarns are used principally for electrical equipment; insulation for wires, cables, mo tors, generators, and transformers. Because all the raw materials for making fibrous glass are abundant within the United States, this miracle filament has entered into the war production program in numerous secret ways to replace scarce mica, asbestos, cork, and aluminum. War has encouraged use as filters for blood plasma kits, wicks for oil lamps, and tracer threads in surgical sponges. If you would let your imagination run riot, think how the whole earth might be bound around with the millions of miles of twine an Olympian glassmaker could melt from the infinite sands of any big bathing beach. Sponge glass and spun glass seem ingenious because they are new. But glass itself would be miraculous were we to come upon it afresh. Many inventions have contributed to man's comfort, convenience, and efficiency. None has helped him more than glass in his quest for knowledge and understanding of the world - and the universe-in which he lives. Feats of Aladdin, Incorporated With glass man sees stars spin and microbes squirm. He can focus a pinpoint of matter, or examine details of the valleys of the moon. Besides seeing infinitely far, and discerning incredibly small objects, he can peer through opaque walls, trap or filter out all sorts of rays, and, with the help of the glass eye of a camera, even behold things that may no longer be there (page 37).