SECRET OF THE GAS MANTLE.
How It Is Made, and Why It Does Not Burn Out. PROBABLY no one who has seen the flimsy white mantle that hangs about the flame of the up-to-date gas light, says an exchange, has failed to wonder of what material this non-combustible affair is made. It looks so like tissue paper, that despite reason one almost expects it to flash up in flame at any moment. It is made of an ash consisting mainly of the oxides of certain rare metals. These metals are lanthanum, yttrium, zirconium, and others, which are rendered incandescent by heating to a high temperature. A six-cord cotton thread is woven on a knitting machine into a tube of knitted fabric of a rather open mesh. This web has the grease and dirt thoroughly washed out and is dried and cut into lengths double that required for a single mantle. It is then saturated in a solution containing the requisite oxides, wrung out, stretched over spools and dried. Next, the double length pieces are cut into two, the top of each piece is doubled back and sewed with a platinum wire, which draws the top in and provides a means of supporting the mantle when finished from the wire holder. After stretching the mantle over a form, smoothing it down and fastening the platinum wire to the wire mantle holder, the mantle is burned out by touching a “Bunsen” burner to the top. The cotton burns off slowly, leaving a skeleton mantle of metallic oxides, which preserves the exact shape and detail of every cotton fiber. The soft oxides are then hardened in a “Bunsen” flame.