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Electric furnace for non-ferrous metals
84
CURRENT TOVlCS.
Durobax: A New Glass for Gauge Glasses.
H. THIENE.
(Zeitschr. Instrumentenk. Beib., xvi, I 6 5 . ) - - T h e desirable qualities of a boiler gauge-glass are: strength to resist pressure, insensitiveness to boiler fluctuations, and immunity to chemical action of steam or feed-water. Practically all gauge-glasses will stand 2oo to 30o atmospheres in the cold state. Heated up to boiler temperature and sprayed at regular periods, the strengths are considerably decreased and vary greatly; thus French will stand 6 atmospheres; English, 7 ; Verbund-Robax, 15 ; Durax, 27 ; and Durobax, 31 atmospheres. The makers of Durobax seem to have improved on their resistance to attack by steam and feed-water, as their gauge-glasses remain clear for a long time. Electric F u r n a c e for Non-ferrous Metals. (Mecl~. Eng., xxx, I 2 5 . ) - - T h i s type of resistance furnace, or a combination of arc and resistance furnace, is the invention of R. S. Wile and has been developed by the Pittsburgh Electric Furnace Company. Four carbon electrodes are used, two through the bottom and two through the top. The specialty is that when preparing to make a heat the furnace is partially filled with broken glass, and the carbon electrodes are arranged so that an arc is formed which melts the glass. As the glass becomes molten it acts as a conductor, and when it is very fluid the electrodes are moved farther apart and the metal is charged into the furnace; this sinks to the bottom, and the fluid glass protects it from oxidation. The glass can be used for several months. In melting brass scrap the loss can be kept as low as I ~ per cent.
Permanent Fireproofing of Cotton Goods.
W. H. PERKIN.
(Eighth International Cong. Appl. Che~.)--A description is given of the series of experiments which led to the commercial production of permanently fireproofed flannelette. The first process worked on a commercial scale consisted in treating the material successively with sodium stannate and with a mixture of sodium tungstate, zinc acetate, and acetic acid. The treated material, however, tended to become damp, the fireproofing was not sufficiently permanent, and the cost of the process was too high. The process finally arrived at was this: the flannelette is impregnated with a solution of sodium stannate of about 45 ° Twaddell, squeezed, dried on heated copper drums, passed through a solution of ammonium sulphate of about 15 ° Tw. to precipitate the tin oxide, again squeezed and dried, washed to remove the sodium sulphate, dried, and finished as usual. The tin oxide is probably present in actual combination with the fibre, for the fireproofing is not destroyed by repeated washing with hot water and soap. The treated material can be dyed the most delicate shades, exerts no deleterious action on the skin, and is stated to be stronger and more durable than the untreated material. With tin at ~2IO per ton, the cost of the process is not more than Id. per yard. The process is applicable to muslin, lace curtains, etc.
CURRENT TOVlCS.
Durobax: A New Glass for Gauge Glasses.
H. THIENE.
(Zeitschr. Instrumentenk. Beib., xvi, I 6 5 . ) - - T h e desirable qualities of a boiler gauge-glass are: strength to resist pressure, insensitiveness to boiler fluctuations, and immunity to chemical action of steam or feed-water. Practically all gauge-glasses will stand 2oo to 30o atmospheres in the cold state. Heated up to boiler temperature and sprayed at regular periods, the strengths are considerably decreased and vary greatly; thus French will stand 6 atmospheres; English, 7 ; Verbund-Robax, 15 ; Durax, 27 ; and Durobax, 31 atmospheres. The makers of Durobax seem to have improved on their resistance to attack by steam and feed-water, as their gauge-glasses remain clear for a long time. Electric F u r n a c e for Non-ferrous Metals. (Mecl~. Eng., xxx, I 2 5 . ) - - T h i s type of resistance furnace, or a combination of arc and resistance furnace, is the invention of R. S. Wile and has been developed by the Pittsburgh Electric Furnace Company. Four carbon electrodes are used, two through the bottom and two through the top. The specialty is that when preparing to make a heat the furnace is partially filled with broken glass, and the carbon electrodes are arranged so that an arc is formed which melts the glass. As the glass becomes molten it acts as a conductor, and when it is very fluid the electrodes are moved farther apart and the metal is charged into the furnace; this sinks to the bottom, and the fluid glass protects it from oxidation. The glass can be used for several months. In melting brass scrap the loss can be kept as low as I ~ per cent.
Permanent Fireproofing of Cotton Goods.
W. H. PERKIN.
(Eighth International Cong. Appl. Che~.)--A description is given of the series of experiments which led to the commercial production of permanently fireproofed flannelette. The first process worked on a commercial scale consisted in treating the material successively with sodium stannate and with a mixture of sodium tungstate, zinc acetate, and acetic acid. The treated material, however, tended to become damp, the fireproofing was not sufficiently permanent, and the cost of the process was too high. The process finally arrived at was this: the flannelette is impregnated with a solution of sodium stannate of about 45 ° Twaddell, squeezed, dried on heated copper drums, passed through a solution of ammonium sulphate of about 15 ° Tw. to precipitate the tin oxide, again squeezed and dried, washed to remove the sodium sulphate, dried, and finished as usual. The tin oxide is probably present in actual combination with the fibre, for the fireproofing is not destroyed by repeated washing with hot water and soap. The treated material can be dyed the most delicate shades, exerts no deleterious action on the skin, and is stated to be stronger and more durable than the untreated material. With tin at ~2IO per ton, the cost of the process is not more than Id. per yard. The process is applicable to muslin, lace curtains, etc.