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Delta rays
86
CURRENT TOPICS. Fireproofing and Insulation
of Wood.
M. DE KEYHEL.
(Rev. Chim. Ind., xxiii, I52.)--This is a discussion of principles, methods, and materials, from which the conclusion is reached that impregnation under pressure is the most efficient method. As a general principle each species of wood requires a different pressure for the necessary penetration, but the pressure remains constant for the same species, regardless of the dimensions of the piece to be impregnated. The penetration of the wood by a crystalloidal liquid is a function of the time. When displacement and penetration take place in a longitudinal sense, irrespective of pressure, the rapidity or duration of the injection will always be in direct relation to the length; for a given length and constant pressure, for the same species, the rapidity may, in certain cases, vary with the initial capillary speed, depending on the concentration of the injected solution. The species generally used are oak, mahogany, teak, ash, beech, gum, walnut, poplar, fir, pitch pine, pine, and birch. The double phosphate of zinc and ammonia obtained by dissolving zinc hydroxide in ammonium hydroxide, and adding phosphoric acid, is superior to any other salt for impregnation, and is the only one that can be applied without inconvenience. The method of making it on a large scale is given. Soldering Lead Pipes with Lead. ANON. (Amer. Mach., xxxvn, 4, ISI.)--The soldering of lead pipes with lead or "leadburning" was known and practised in the Middle Ages. Vincent de Beauvais, who died in 1264, wrote: " I f tin is exposed to a moist atmosphere, it will corrode; but human ingenuity has of late invented useful improvements by which it is possible to unite leaden subterranean water pipes with the aid of molten lead instead of soldering with tin. Pipes soldered with the latter metal never lasted long, but if lead is used it will last for all time." The
(Oesterr.
Preservation
of W o o d
with
"Bellit."
NOWOTNY.
Chem. Zig., xv, IOO.)--Sodium fluoride is mixed with
nitro-phenols to increase its preservative effect. One of these compounds, known as " Bellit," consists of 9 ° parts of 90 to 95 per cent. sodium fluoride with IO parts of dinitrophenolaniline. This latter is an active antiseptic and has no action on the iron vessels used for impregnating. The selective phenomena observed with mixtures of zinc fluoride and hydrochloric acid are also observed in the "Bellit" process. Delta Rays. N. CAMPBELL. (Phil. Mag., ~xxiii, 46.)--The speed of the ~-rays is independent of the speed of the a -rays which excite them, as well as of the material from which they emanate. The magnetic methods hitherto used to measure the speed of the ~-rays are considered somewhat untrustworthy.
CURRENT TOPICS. Fireproofing and Insulation
of Wood.
M. DE KEYHEL.
(Rev. Chim. Ind., xxiii, I52.)--This is a discussion of principles, methods, and materials, from which the conclusion is reached that impregnation under pressure is the most efficient method. As a general principle each species of wood requires a different pressure for the necessary penetration, but the pressure remains constant for the same species, regardless of the dimensions of the piece to be impregnated. The penetration of the wood by a crystalloidal liquid is a function of the time. When displacement and penetration take place in a longitudinal sense, irrespective of pressure, the rapidity or duration of the injection will always be in direct relation to the length; for a given length and constant pressure, for the same species, the rapidity may, in certain cases, vary with the initial capillary speed, depending on the concentration of the injected solution. The species generally used are oak, mahogany, teak, ash, beech, gum, walnut, poplar, fir, pitch pine, pine, and birch. The double phosphate of zinc and ammonia obtained by dissolving zinc hydroxide in ammonium hydroxide, and adding phosphoric acid, is superior to any other salt for impregnation, and is the only one that can be applied without inconvenience. The method of making it on a large scale is given. Soldering Lead Pipes with Lead. ANON. (Amer. Mach., xxxvn, 4, ISI.)--The soldering of lead pipes with lead or "leadburning" was known and practised in the Middle Ages. Vincent de Beauvais, who died in 1264, wrote: " I f tin is exposed to a moist atmosphere, it will corrode; but human ingenuity has of late invented useful improvements by which it is possible to unite leaden subterranean water pipes with the aid of molten lead instead of soldering with tin. Pipes soldered with the latter metal never lasted long, but if lead is used it will last for all time." The
(Oesterr.
Preservation
of W o o d
with
"Bellit."
NOWOTNY.
Chem. Zig., xv, IOO.)--Sodium fluoride is mixed with
nitro-phenols to increase its preservative effect. One of these compounds, known as " Bellit," consists of 9 ° parts of 90 to 95 per cent. sodium fluoride with IO parts of dinitrophenolaniline. This latter is an active antiseptic and has no action on the iron vessels used for impregnating. The selective phenomena observed with mixtures of zinc fluoride and hydrochloric acid are also observed in the "Bellit" process. Delta Rays. N. CAMPBELL. (Phil. Mag., ~xxiii, 46.)--The speed of the ~-rays is independent of the speed of the a -rays which excite them, as well as of the material from which they emanate. The magnetic methods hitherto used to measure the speed of the ~-rays are considered somewhat untrustworthy.