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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I A T E E R I N G C H E M I S T R Y .
pressure. The iron or steel objects become coated with a carbon and iron compound possessing a blue color when the objects are removed from the furnace; when cool, a thin coating of linseed oil is applied, changing the color to a deep black. The coating is said to resemble t h a t produced by the Bower-Barff process in appearance, and t o have a hardness of about 9. A Pittsburgh manufacturing firm has for some time been making a special study of slow-corroding steel for pipe, and is reported to have succeeded in developing a soft steel having a n exceptionally high degree of uniformity. This is said t o have, been further improved by a patented process of hot forging, known as spellerzzing, which is applied to the metal in the course of manufacture, and which renders the surface more uniformly dense and less liable t o become pitted. It is claimed t h a t this steel will give good service in cases where no protective coating can be applied. To protect pipe from moisture, the same company has developed a coating to be applied t o pipe ranging from 3 to 18‘/* inches in diameter. The Coslettizing process, said t o produce a black, rust-proof finish on iron, consists in boiling the article in a solution of I ounce of iron filings and 4 ounces of phosphoric acid in I gallan of water. LOHMANNIZING. The protection of iron and steel is a t present effected by means of three dnc coating processes: the old “hot galvanizing” process, the “cold galvanizing” process (electrolytic zinc plating), a n d the “sherardizing” process (see Met. Chem. Ind., 6, 189; IO, 253). The process of “Lohmannizing,” invented by H. J. Lohmann, differs from these in that i t is not restricted to the application of ziqc coatings, b u t may, it is claimed, be used for coatings of zinc, lead, and tin in varying preparations t o suit the requirements of each case. The process of Lohmannizing begins, as usually, with pickling the iron and steel articles in a bath of sulphuric acid. Then the article is dipped into the Lohmann bath, which, being “composed of a n acid and a n amalgamated salt, further cleanses the pores and cavities, and deposits metallic salt upon the entire surface, penetrating into the most minute pores and cavities.” The patent specification states that the Lohmann bath is a solution of hydrochloric acid, mercuric chloride, and ammonium chloride. Next follows drying and then immersion in the molten protective alloy which is at a temperature of 950 t o IOOOOF. “An amalgam or chemical union is thus formed between the amalgamating salt and the protective alloy.” The temperature of the immersed article rises in contact with the molten alloy, and, when i t reaches a temperature of 5ooo, volatilization of the mercury occurs. Since the mercury passes from the surface of the alloy, the complete surface is said to be left free and open for the protective alloy to fill its pores and cavities, there being freedom from oxidizing influences. As i t is said t h a t it is possible to obtain a perfcctly satisfactory lead plating by the Lohmann process, it would seem that the process would be of value in the production of lead-lined apparatus.
THE INFLUENCE OF ADDITIONS TO BRONZE. Bronze composed of copper and up to zo per cent. of tin is usually specified for monumental work. It has been found, however, t h a t the shrinkage of these pure copper-tin bronzes is considerable, and since it militates against the precise jointing of large bronze works of art cast in several pieces, undesirable experiences have been the result. Von Miller [Metalluvgie, 9, 63 ( I ~ I Z ) ]aftersexperimenting , on a bronze composed of gz per cent. of copper and 8 per cent. of tin, has come to the following conclusions: Shrinkage can be appreciably diminished only by the addition of about I O per cent. of zinc in the presence of tin. Cobalt, aluminium, silicon, iron, and nickel ’
May, 1912
increase the shrinkage. Tensile strength is increased by cobalt, ‘ nickel and manganese, but is considerably lowered by antimony and zinc. Cutting, boring, chiseling and engraving are rendered, easier by up to z per cent. of antimony and lead, and more‘ dificult by nickel and manganese. The addition of tungsten, nickel, iron, manganese or cobalt raises the melting point. The formation of,a patina is less on bronzes containing zinc and aluminium, but is greater on those containing cobalt, nickel, antimony, iron, silicon, or phosphorus than on a normal coppertin bronze. Patina formation was tested for with a weak soh-‘ tion of ammonium sulphydrate containing sulphur. COPPER FUNGICIDES. Pickering Agric. Sci., 4, 273 ( I ~ I Z ) points ] out t h a t the most effective form of Bordeaux mixture is obtained by adding, lime water to copper sulphate until just short of alkalinity, This b a s k splphate, which possesses. the formula I O CuO.SO, and is known as Woburn Bordeaux, has been shown by di-ect, experiments to be e n t t o 6 times the weight of ordinary Bordeaux. Accor Pickering, the copper in Bordeaux, mixture is r e n d q le by the carbon dioxide, and dissolved copper is invariably present in the drip water collected from trees which have been sprayed. Gimingham and Barker ( J . SOC.Cheni. Ind., 1911,760) have suggested t h a t the solvent of the nrmnally insoluble copper compound is a substance excreted by the fungus itself; but this is denied by Pickering and experiments are described t o prove t h a t t h e copper in Bordeaux mixture is brought into the soluble condition by the action .of air. Pickering shows t h a t the greater the excess of lime] present the longer is the interval before this action commences; t h a t Bordeaux mixture does not dissolve sufficiently t o give a reaction for copper with ferrocyanide, although it does dissolve enough t o react with iron; t h a t an atmosphere of carbon dioxide greatly accelerates action, but until the carbon dioxide actually reaches a certain proportion a reduction of action is noticed; and t h a t action is also increased by the presence of calcium sulphate. It would appear t h a t if fungicidal action were dependent upon a solvent material exuded from the fungus, all basic sulphates and carbonates of copper would be equally efficacious for a given weight of copper present; but, as shown by Pickering, this+is not the case.
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THE UTILIZATION OF THE POTASSIUM CONTENT ,OF b * r‘ I’ I f ’ I MINERALS. Aschan [Z. anorg. Chem., 74, jj (1912)l has recently investigated the utilization of the potassium contents of the “Rapakivi” and pegmatite granites. He has found t h a t the potassium present in the feldspar may be rendered soluble in water by fusing the powder with anhydrous calcium chloride or with lime and sodium chloride (see, in this connection, Rhodin, /. SOC.C h e m Ind , 1901,431),and both methods are considered of possible value in rendering the potassium available for agricultural purposes, the former presenting distinct advantages if the calcium chloride is obtainable cheaply. Aschan found t h a t the greater part of the potassium in feldspar may also be rendered soluble, as hydroxide, by heating under pressure with lime and water. He found t h a t treatment with acids was unsuitable.
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PURIFICATION O F WATER BY FORCED OXIDATION. It is reported t h a t at Cardiff, Reading, Tunbridge Wells, and elsewhere in Great Britain, a new system of purifying water is in operation, and the results have, so far, been apparently satisfactory. The “Candy” apparatus consists of a steel cylinder, the lower portion of which contains the filtering media-fine silica grit, sand, and a special oxidizing substance termed “oxidium.” A special correspondent of Metalluvgical and
