. Electric railway journal . 1094 ELECTRIC RAILWAY JOURNAL [Vol. XLVIII, No. 22 and the crucible containing the copper rests on the bot-tom between the two arcs. The operation of the furnaces is as follows: Beforethe current is turned on, all the carbon terminals arelowered until contact is made with the granular carbonbed. The current is then applied through the startingresistance, and the arc terminals are raised until arcsof proper length are obtained. The length of the arc isjudged by the drop in potential across the terminals ofthe furnace, a voltmeter being provided for this
. Electric railway journal . 1094 ELECTRIC RAILWAY JOURNAL [Vol. XLVIII, No. 22 and the crucible containing the copper rests on the bot-tom between the two arcs. The operation of the furnaces is as follows: Beforethe current is turned on, all the carbon terminals arelowered until contact is made with the granular carbonbed. The current is then applied through the startingresistance, and the arc terminals are raised until arcsof proper length are obtained. The length of the arc isjudged by the drop in potential across the terminals ofthe furnace, a voltmeter being provided for this the arcs are established the starting resistance isshort-circuited. The three furnaces are connected inseries across a 600-volt circuit, and an average currentof about 200 amp. is used. Heats can be made everythirty minutes. The difficulties in obtaining pure copper and in get-ting satisfactory deliveries owing to the market condi-tions caused by the European war led to the develop-ment of the second method of bonding. The
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