National Geographic : 1940 Nov
DEATH SENTENCE for Dirt 4 *ldi% 9 hae * Severalyears ago one of the most in teresting experimental devices in our re search laboratory was one that acted like a magnet on smoke, dust and dirt in the air. Strange part about this electric device was that it worked just as quietly and free from moving parts as a storage battery. Yet in practically no time at all it would collect a jar full of dirt from air you'd declare was clean and pure. * Today, that device is known as the Precipitron* and we're having a busy time filling orders for it. That's easy to under stand once you appreciate that the great American smoke problem alone costs busi ness, home owners and taxpayers millions of dollars each year. But smoke is only one of innumerable air-borne impurities such as dust, dirt, pollen and other substances. * The way the Precipitron rids the air of smoke is an interesting example of its practical efficiency and usefulness. Smoke is made up of particles so minute that a screen fine enough to catch them would not allow air to pass. * Yet the Precipitrontakes smoke out of the air as if by magic. The principle employed is simple. Every incoming par ticle of smoke, dust, dirt, and pollen re ceives a positive electrical charge. Then a negatively charged plate, acting like a mag net on steel filings, draws these particles out of the air stream. * We knew that there was a need for the Precipitron, but we hardly expected it would find so many uses as to open up an entirely new industry for us. * Forinstance, in textile mills the Pre cipitron is removing smoke and soot from the air for the dryer and spinning rooms. In telephone exchanges it is protecting the tiny, delicate relays that operate the dial telephone system. In steel mills it is clean ing the ventilating airfor main-drive motors and motor generator sets. In hospitals it is safeguarding recovery wards and operat ing rooms. * In all buildings where installed, it is reducing cleaning and painting costs. One store which used to repaint every year now finds it need do so only once in three years. * Right now Westinghouse Research Engineers are working on many other diffi cult projects. We hope a lot of things like the Precipitron will result. *Registered Trademark "Mention the Geographic-It identifies you."