Electrochemical and metallurgical industry . lcium, was probably due to thesmall scale on which the operation was tried. The simple andsatisfactory operation of this furnace would lead one to believethat, technically, the process would be still more efficient andeasily controlled. A furnace, five times as large, using about1200 amperes, would require about 8 volts, and the screwmechanism could be electrically controlled, keeping the cur-rent constant and the product perfectly uniform, as the rotaryfurnaces of the Union Carbide Co. are controlled. A water-cooled shield might be necessary to coo
Electrochemical and metallurgical industry . lcium, was probably due to thesmall scale on which the operation was tried. The simple andsatisfactory operation of this furnace would lead one to believethat, technically, the process would be still more efficient andeasily controlled. A furnace, five times as large, using about1200 amperes, would require about 8 volts, and the screwmechanism could be electrically controlled, keeping the cur-rent constant and the product perfectly uniform, as the rotaryfurnaces of the Union Carbide Co. are controlled. A water-cooled shield might be necessary to cool the large calciumcathode as it was drawn from the bath. The two essentialconditions of operation are—first, rapid withdrawal of themetal formed to increase the yield and minimize recombina-tion ; second, narrow temperature limits. The bath must behot enough to deposit the metal molten, not spongy, and coolenough to let it congeal upon the cathode and be raised with-out breaking off. The solid metal can be worked like other metals and is. 5.—ELECTRIC FURNACEPRODUCING CALCIUM. FOR much more stable than imagined. It can be heated red-hotcontinuously in a triple Bunsen flame without igniting, butat this temperature its texture is like clay, and it can be easilysqueezed apart with tongs, sometimes igniting at the edgesand burning feebly till the lime formed smothers the cold, a bright calcium surface becomes didl rapidly inordinary air, but if hot the metal can be brightened with afile or polished in the lathe with emery cloth and will remainbright as long as it is hot. The specific gravity is ° C, so that it is only four-sevenths as heavy as the lightmetal aluminium (specific gravity ). Calcium is the fifthbest conductor of electricity, being surpassed by silver, copper,gold and aluminium, if wires of equal diameter and lengthare compared ; but for wires of equal weight and length theorder is entirely different, calcium being second and exceed-ing
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