\/A' WILLIAM SIEMENS, F.R.S. 225 



in< reusing the power of tlie dynamo-electric machine and the size 

 <>f the crucil)le8. (These remarks were illustrated by an actual 

 arrangement on the plan described, and 1 Ib. weight of broken 

 lilcs, which wt-re placed in a crucible through which a dynamo- 

 riujvnt of aliout 70 webers was passed, was brought to a liquid 

 in thirteen minutes, and poured out of the crucible in that 

 oondition.) 



I'.y the use of a pole of dense carbon, the otherwise purely 

 dirmical reaction intended to be carried into effect may be inter- 

 fered with through the detachment of particles of carbon from 

 the same ; and although the consumption of the negative pole in 

 a neutral atmosphere is exceedingly slow, it may become necessary 

 to substitute for the same a negative pole so constituted as not to 

 yield any substance to the arc. I have used for this purpose (as 

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

 copper, through which a cooling current of water is made to cir- 

 culate. 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 of small sec- 

 tional area, the escape of current from the pole to the reservoir is 

 so slight that it may be entirely neglected. On the other hand, 

 some loss of heat is incurred through conduction in 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. 



The dynamo-electric machine consuming 4*25 horse-power, or 

 8'17 ergtens, per second, will send a current of 40'5 webers through 

 1 unit electrical resistance ; replacing the resistance by an arc 

 maintained by the balance-weight constantly at 37 '8 volts electro- 

 motive force, the same current will flow. 



Neglecting the connecting wires, there will be developed in the 

 arc an energy of 1, 531'2 xlO 7 ergs, per second = 1), 1 H7'2 x 10 8 

 ergs, per minute, or 1,378*1 x 10 10 ergs, per 15 minutes = 32-x x 

 1<> 1 -rani water degree units of heat. 



.ining steel to have the same specific heat as iron, viz., ah 

 *> = 0-1040x0-000144 *, and that the melting point of steel is 

 1800 C., then 420'5 units of heat will be expended in raising the 



VOL. II. Q 



