Aluminum and Copper

In one of his recent prophetic effusions Nikola Tesla predicted that copper would in time be wholly superseded by aluminum. With the present high price of copper and the comparatively reasonable price of aluminum one might expect this to come true, but the new metal is not yet enough of a rival even to affect the copper market. The reason for this is explained by Prof. John Trowbridge of Harvard.

While the price of aluminum has fallen from $90 a pound to 65 cents a pound, and while its powers of conductivity are double those of copper for the same weight, it is still comparatively useless in electrical work because of the difficulty of soldering or brazing two pieces of the metal together. In order to transmit the current without great loss the trolley lines or telegraph and telephone wires must be perfectly joined where one section is spliced to the next. This apparently trivial difficulty has thus far prevented the use of aluminum in overhead electric wires of any kind.

Still more serious is the barrier to its use in electric cables, for in order to compete with copper the wire must be nearly twice as thick. This increases the size of the cables in a way that is detrimental to the proper transmission of the electrical waves. In general the conducting part of all electrical apparatus would have to be nearly twice as big if aluminum wire were nsed. These facts, together with the extra difficulty of working aluminum, have thus far prevented its many good qualities from making it a serious rival of copper. Thus far Tesla stands discredited as a prophet, but the future may change all that. A chemist in the bronze age might have scouted the idea that iron, with its tendency to rust over night, would ever supersede bronze.