. Transactions. ole mag-net there is the greatest scattering of lines of force, with thedouble-pole magnet the greatest concentration, hence for agiven electric current the attraction per sq. cm. of field in asingle-pole magnet is much smaller, about 60 per cent., than inthe double-pole magnet, as long as the air-gap between the twopoles is not too large. The current for the magnets is taken by a shunt from the110-volt electric-light main. In order to reduce it to the re-quired strength, an incandescent lamp of eight candle powerstrength is placed in the circuit. From the magnet the currentpas
. Transactions. ole mag-net there is the greatest scattering of lines of force, with thedouble-pole magnet the greatest concentration, hence for agiven electric current the attraction per sq. cm. of field in asingle-pole magnet is much smaller, about 60 per cent., than inthe double-pole magnet, as long as the air-gap between the twopoles is not too large. The current for the magnets is taken by a shunt from the110-volt electric-light main. In order to reduce it to the re-quired strength, an incandescent lamp of eight candle powerstrength is placed in the circuit. From the magnet the currentpasses through a Weston direct-reading ammeter back to themain. A switch is placed in the circuit to permit the currentto be turned on and off. In a test the ore was spread out on a piece of glazed paper,the current turned on, the single-pole magnet passed to and MPAH LTIOB 01 I Bl I \m;-.\i \i.« ,, over *• ore with raising and lowering, and then movedto one Bldei ,1m (^l»< switched off and the adherii ? 2* +1-H-U- 2M- Double-Pole Electro-Magnet. dropped onto a paper. Another layer of ore was then spreadover the first glazed paper, and the operations repeated until a 984 8BPARATI0M OF \ BLBNDB-MAROASITB CONCENTRATE. batch had been treated. The first magnetic concentrates werethen retreated until they had been freed from the non-magneticparticles that had been carried along mechanically. As arule the tailings from the single-pole magnet were treated withthe double-pole magnet, the manipulation being the same as inthe first operation. The zinc in the ore and the tailings was determined bytitrating with potassium ferroeyanide as worked out by vonSchulz and Low in With the magnetic concentrates,which run high in iron and are not decomposed by treatmentwith nitric acid and potassium chlorate, solution with nitro-hydrochloric acid had to be substituted. The iron was con-verted into sulphate and titrated with potassium permanganate. IV. Experiment with 8-Mesh Material. 1
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
