‘METALLIC WIRES BY ELECTRICITY. 435 
The temperature of the thin wire 15 lines in length would 
therefore be 0°6792 for unity of charge. and for the destruction 
of the wire 239°6 and 245-2 degrees. It is remarkable that these 
temperatures are in no way less than those found previously. 
For when, as is really the case, the observations on the thick 
wire give a higher temperature for the thin wire than the obser- 
vations on the thin wire itself, the supposition is thereby con- 
tradicted, that the retarding power of the thin wire does not 
decrease in a constant ratio with its diminution in length, but 
only within a certain limit, which is above the length of 15 lines. 
It must also be noticed, that the temperatures at which this wire 
was destroyed are rather too high than too low, as the calcula- 
tion has been made for the discharge of the whole quantity of 
electricity contained in the battery, although, as will be shown 
hereafter, no inconsiderable portion of that quantity remains 
behind in the battery after the discharge. 
It requires no very extended process of reasoning to show that 
the temperature of 245 degrees (the highest calculated from any 
single experiment) is not that really possessed by platina fused 
by means of electricity. By a smaller quantity of electricity 
than that here used, platina is fused into small shining globules, 
which are often so firmly melted into the sides of a glass tube 
held at a quarter of an inch distance, as only to be removed by 
fracture of the glass. The detailed experiments prove that the 
electrical fusion of metals is no secondary phenomenon to their 
being heated, and that a metal actually melts long before the 
rise in its temperature would cause it to do so. We must there- 
fore acknowledge in the fusion an electrical action distinctly 
separate from that causing heat by electricity, the laws regu- 
lating which action must be studied apart. This separation of 
the two phznomena, which has thus been indirectly found, may 
be seen in a clear and direct manner, if the attention be directed 
to the state of the wire exposed to the electrical discharge during 
its transition from a normal rise in temperature to the melting- 
point. Before that power of discharge has been attained which 
would cause the wire to become red-hot, peculiar changes in the 
appearance of the wire occur; and in the same way before it 
reaches the melting-point it is affected in a manner, having no 
resemblance to that produced by a mere rise of temperature. 
