Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1918 edition. Excerpt: ...process has not been able to displace the older process of distillation. Lead The only process which has been working successfully for any length of time is that of Pedro G. Salom, for obtaining 1 Zeitsch. anorg. Chem., 1901, 27, 177. 2 Zeitsch. anorg. Chem., 1896, 12, 272; Electrochem. Ind., 1905, 3, 63. 3 Trans. Amer. Electrochem., 1902,1, 141. metallic lead from galena.1 The process has been worked by the Electrical Lead Reduction Company at Niagara for some years. Powdered galena is packed on antimonial-lead trays (Fig. 22), each tray is insulated from those next it by rubber rings, and is filled two-thirds full of dilute sulphuric acid, so that the powdered ore is. / covered by it; the bottom of each tray is in contact with the acid beneath it. Generally, forty to fifty trays are arranged in series, and the top and bottom ones connected to the source of current, so that the intermediate trays act as bipolar electrodes which are negative on the top, or galena side, and positive on the bottom. Electrolysis takes place and the hydrogen liberated from each tray reacts with the galena forming hydrogen sulphide and metallic lead--PbS + H2 = Pb + H2S. The spongy lead produced is usually roasted to oxide (litharge), and its average purity is 97 per cent. About 2-5 volts are used per cell, and one ampere per pound of metal produced. Lead is now being separated in the United States by roasting galena with salt, after which, the solution obtained by leaching with brine is electrolysed.2 Nickel The Hoepfner process, similar in principle to the Hoepfner process for copper winning, was almost the first process to be used. Roasted nickel ore was extracted with calcium chloride 1 Electrochem. Ind., 1902, 1, 18; Trans. Amer. Electrochem., 1902, 1, ..