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Solder for aluminum
408
CURRENT ToPicS.
wooden racks on a shelf in proximity to an inclosed arc light; beginning with a pure oil on the left hand side, then bottles with o.I per cent. mineral oil, I per cent., 2 per cent., etc., up to IO per cent. The standard with linseed oil serves to examine cottonseed, corn, China-wood, China-bean oils, or any other non-fluorescent vegetable oil. The special standard of lard oil is necessary to test adulterated lard oils. Materials for Balloon Envelopes and for Producing Gastightness. H. HOERNES. (Gummi-Zeit., xxv, I 2 8 I . ) - - T h e materials used for balloon envelopes are : ( I ) Pongee Silk. Its advantages are its great tensile strength combined with lightness; its disadvantages are its high cost, its tendency to brittleness, and its electrical properties. (2) Cottons, such as Percale or Calico. Their advantages over silk are greater stability as regards atmospheric influences, but they are less strong and much heavier. Generally employed as a double layer of the fabric, with the threads either parallel or at an angle of 45 ° to one another, joined by an intermediate layer of rubber. (3) Fine Linen. Almost as costly as silk, but not as light, and therefore not desirable. (4) Gold-beater's Skin is very expensive, difficult to repair, and sensitive to atmospheric influences. Advantageous on account of low porosity and its high tensile strength per unit weight. (5) ,41uminum is used in strips of sheet about 0.2 mm. thick, riveted or welded together. The materials for gas-tightness are : ( I ) Linseed Oil Varnish. Advantageous on account of low cost and ease of application and great efficiency. Objections are the need of constant attention during storage, risk of spontaneous inflammation if the air supply is insufficient, the slowness of the repairing process and tackiness at an elevated temperature. (2) Rubber. Used as a layer of vulcanized rubber between the layers of fabric. Repairs effected easily and rapidly, the fabric is always supple and there is no tackiness at high temperatures. On the other hand, it is high priced, susceptible to electric discharges. very heavy, and easily affected by the violet and ultra-violet rays. Other gas-tight materials are Ballonin, a solution of gutta-percha in benzol; Konjaku, a Japanese vegetable product, put on the market as a white powder, soluble in warm water; Bi-chromated Gelatin; and Pegamoid. Solder for Aluminum. N . J . A . BOURGADE. (French Patent, 425, 912, I 9 i o . ) - - T h e solder is composed of an alloy of I part tin and 2 parts zinc, to which 5 per cent. of its weight of cadmium is added. These proportions are variable. The solder can be used without a cleansing agent or solvent for oxide. The Influence of Surface on the Rusting of Iron.
K. ARNDT.
(Metallurgie, viii, 353.)--The electrolytic theory of the rusting of iron is discussed in relation to the varieties of iron, such as cast iron
CURRENT ToPicS.
wooden racks on a shelf in proximity to an inclosed arc light; beginning with a pure oil on the left hand side, then bottles with o.I per cent. mineral oil, I per cent., 2 per cent., etc., up to IO per cent. The standard with linseed oil serves to examine cottonseed, corn, China-wood, China-bean oils, or any other non-fluorescent vegetable oil. The special standard of lard oil is necessary to test adulterated lard oils. Materials for Balloon Envelopes and for Producing Gastightness. H. HOERNES. (Gummi-Zeit., xxv, I 2 8 I . ) - - T h e materials used for balloon envelopes are : ( I ) Pongee Silk. Its advantages are its great tensile strength combined with lightness; its disadvantages are its high cost, its tendency to brittleness, and its electrical properties. (2) Cottons, such as Percale or Calico. Their advantages over silk are greater stability as regards atmospheric influences, but they are less strong and much heavier. Generally employed as a double layer of the fabric, with the threads either parallel or at an angle of 45 ° to one another, joined by an intermediate layer of rubber. (3) Fine Linen. Almost as costly as silk, but not as light, and therefore not desirable. (4) Gold-beater's Skin is very expensive, difficult to repair, and sensitive to atmospheric influences. Advantageous on account of low porosity and its high tensile strength per unit weight. (5) ,41uminum is used in strips of sheet about 0.2 mm. thick, riveted or welded together. The materials for gas-tightness are : ( I ) Linseed Oil Varnish. Advantageous on account of low cost and ease of application and great efficiency. Objections are the need of constant attention during storage, risk of spontaneous inflammation if the air supply is insufficient, the slowness of the repairing process and tackiness at an elevated temperature. (2) Rubber. Used as a layer of vulcanized rubber between the layers of fabric. Repairs effected easily and rapidly, the fabric is always supple and there is no tackiness at high temperatures. On the other hand, it is high priced, susceptible to electric discharges. very heavy, and easily affected by the violet and ultra-violet rays. Other gas-tight materials are Ballonin, a solution of gutta-percha in benzol; Konjaku, a Japanese vegetable product, put on the market as a white powder, soluble in warm water; Bi-chromated Gelatin; and Pegamoid. Solder for Aluminum. N . J . A . BOURGADE. (French Patent, 425, 912, I 9 i o . ) - - T h e solder is composed of an alloy of I part tin and 2 parts zinc, to which 5 per cent. of its weight of cadmium is added. These proportions are variable. The solder can be used without a cleansing agent or solvent for oxide. The Influence of Surface on the Rusting of Iron.
K. ARNDT.
(Metallurgie, viii, 353.)--The electrolytic theory of the rusting of iron is discussed in relation to the varieties of iron, such as cast iron