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be heated over a stove. While the shade is still hot a piece of wax or ordinary candle is rubbed over both sides of the brass. The heat of the brass melts the wax and forms a thin wax coating. When the brf,;;a be comes cold, the design, which shows through the wax, is traced with a pointed in�trument. The parts of the brass which are to be burned out are. scraped free of wax. The shade is then immersed in nitric acid. The acid eats through the exposed brass and the required design is verydoi:10.1038/scientificamerican02061909-121f fatcat:kfghmqgarngqxf266m7rwc2dxu