FUSION OF METALS BY VOLTAIC ELECTRICITY. 5 1 



of heat within it. Now the escape of heat may be largely 

 prevented by means of non-conducting substances, and will be 

 nearly proportional to the surfaces, so that by employing 

 sufficiently large masses of metal, and surrounding them with 

 non-conducting materials, it may be reduced to almost any 

 extent. The quantity of zinc required to fuse a large mass 

 of iron may therefore be estimated as follows. — 



I have shown in a paper already communicated to the 

 Society, that the quantity of heat due to the intensity of a 

 Daniell's cell is 6°. 129 per pound of water for every 33 grains 

 of zinc dissolved.* In working with a voltaio battery, it is 

 generally an advantageous arrangement to make the resistance 

 of the battery one-half that of the entire circuit. Hence, 

 as the quantity of heat evolved in any part of the circuit is 

 proportional to its resistance, we may take half the above, or 

 3°.064 per pound of water, as the heat which may be advan- 

 tageously produced outside a Daniell's battery by the 

 dissolution of 33 grains of zinc. Calling the temperature of 

 incipient fusion of iron 4,000° above the ordinary temperature 

 of the atmosphere and the specific heat of iron 0.11, we find 

 4,740 grains of zinc to be the quantity consumed in the voltaic 

 battery, in order to raise one pound of iron to the temperature 

 of fusion. But as a considerable quantity of heat will be 

 rendered " latent," 5,000 grains may be taken as the estimate 

 of minimum consumption of zinc, in a Daniell's battery, in 

 order to effect the fusion of one pound of iron. 



The same effect is due to the heat evolved by the combus- 

 tion of 500 grains of coal, but on account of the large quantity 

 of heat which must necessarily escape up the chimney of a hot 

 furnace, we may estimate the minimum actual consumption at 

 1,000 grains. 



The quantity of zinc consumed in the voltaic process is there- 

 fore nearly equal to that of the iron to be melted, but it would 



* Memoirs of the Literary and Philosophical Society, Vol. vii., p. 94. 



