Siemens and Halske

The sodium reduction process was first implemented in Germany by Siemens and Halske A.G. and it remained a principally European method, while the American tantalum industry was founded exclusively on the electrolysis of molten fluorides [28, 576]. The production of tantalum by sodium reduction has gained worldwide acceptance and currently, nearly 90% of the world s tantalum is produced by the sodium reduction method [538]. 

Various attempts have been made to employ electrolytic methods for the extraction of arsenic from arsenical minerals. Thus Siemens and Halske 3 suggested the treatment of sulphide ores with sulphides or hydrosulphides of the alkali metals so that the arsenic passed into solution as a double sulphide or thioarsenite, thus ... 

Several processes for the extraction of copper by electrometallurgical methods have been devised. The Marchese patent2 aimed at the decomposition of copper matte and deposition of the copper simultaneously in a sulphuric-acid electrolyte with a copper-matte anode and a copper cathode. In Siemens and Halske s patent3 the copper of the ore was oxidized to the cupric state by an acid solution of ferric sulphate, and the copper deposited electrolytically in a second vessel with a diaphragm separating the cathode and the anode. Neither process has been commercially successful. 

Siemens and Halske (D.R.P., 85,103) oxidise ammonia gas hy silent electrical discharges. 

The variation of the temperature of the copper block K, relative to that of the block C, caused by the introduction of the substance, is determined by means of ten copper-constantan couples in series, the electro-motive force being measured by means of a Siemens and Halske millivoltmeter. As these instruments allow very accurate readings to be taken, using a lens if necessary, it was possible to employ one of them instead of a mirror galvanometer. 

Siemens and Halske use as solvent either the sulphides, hydrosulphides, or polysulphides of the alkalis. When the finely ground ore is thus lixiviated, a double salt is formed, e.g. with NaHS... 

Various attempts were made to develop pressure water electrolysers between 1920 and the second world war, but all came short of industrial recognition Noeggerath in 1927 (150 bar), Neiderreither in 1929 (bipolar electrodes, 5 kW), Lawaczek in 1928 (300 bar), Siemens and Halske in the late 30 s (5 to 10 bar). 

Siemens and Halske, equal parts of zinc and cadmium and 10 per cent. Sb. t It can be made thus —Melt separately 4 parts of copper, 12 parts of Banca tin, and 8 parte of antimony regulus, and, after fusion, d 12 parts of tin. The antimony is added to the first portion of the tin after its fusion, and the copper is introduced after the vessel is taken off the fire and before its content is poured out. The charge is kept from oxidation by a layer of powdered charcoal. A small percentage of aluminium added to the mixture gives a good result. 

Siemens and Halske AG, W. Schottky named as inventor, Zur Stromliefemng geeignetes galvanisches Element bzw. Elementkette, DRP 650 224, filed April 6.1935. 

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