OCR Text |
Show Lamp Lore In a modern electric lamp factory fac-tory two main classes of lamps are ' made. The vacuum lamp, to called because every trace of air has been extracted and 'he lamp hermetically hermetical-ly sefiied ; and the pas-filled lamp, where, the air having been similarly similar-ly exhausted. Its place Is taken by an Inert pas. such as arpon or nitro-pen nitro-pen dry and pure to plven pressure. pres-sure. The vacuum Is ohtalned by nse of a mechanical pnmp. nnd by Its means a vacuum of 400.000th of ni atmosphere can be produced. Tlt-Blts Mapazine. |