S/K WILLIAM SIEMENS, F.R.S. 261 



a still larger scale ly inm-asing the power of thedyiiaino-niaehiius 

 and the size of the crucibles. 



The purely chemical reaction intended to be carried into effect 

 within the crucible, might be interfered with through the detach- 

 ment of particles from the dense carbon used for the negative pole, 

 although its consumption within a neutral atmosphere is exceed- 

 ingly slow. To prevent this I have used, both in this connection 

 and also in the construction of electric lamps, a water pole, or tube 

 of copper, through which a current of water circulates, so that it 

 yields no substance to the arc. It consists simply of a stout copper 

 cylinder closed at the lower end, having an inner tube penetrating 

 to near the bottom for the passage of a current of water into the 

 cylinder, which water enters and is discharged by means of flexible 

 India rubber tubing. This tubing being of non-conductive material, 

 and its sectional area small, the escape of current from the pole 

 to the reservoir is so slight that it may be neglected. On the 

 other hand, some loss of heat is incurred through conduction, 

 with the use of the water pole, but this loss diminishes with the 

 increasing heat of the furnace, inasmuch as the arc becomes 

 longer, and the pole is retired more and more into the crucible 

 cover. 



In the experiments which I shall now place before you, the 

 current which has supplied the one electric lamp in the centre 

 of the hall will be diverted by means of a commutator through 

 the electric furnace. After it has been active for five minutes to 

 warm the crucible, I shall charge the furnace with 8 Ibs. of 

 broken steel files, which I shall endeavour to melt and pour out 

 into an ingot mould before your eyes. 



By some obvious modifications of this electric furnace it can 

 be made available for a variety of other purposes where intense 

 heat is required combined with immunity from disturbing 

 chemical actions. By piercing a number of radial holes through 

 the sides of the chamber, and introducing the ends of wires 

 through the same, an excellent means is provided of heating those 

 wire ends very rapidly, without burning them, for the purpose of 

 welding them together. The electrical furnace will also be found 

 useful, I believe, in the hands of the chemist to effect those re- 

 actions between gaseous bodies which require the employment of 

 temperatures far exceeding the hitherto available limits, and will 



