The welding of copper requires a larger sized blowpipe than that for iron of corresponding thickness, by reason of the greater conductivity of copper. A flux is always required, pulverised acidum boricum generally being used for such purpose. The weld should always be mechanically treated as soon as it has cooled.

The welding of copper is a substitute for brazing in copper work of various descriptions. By means of the coal-gas blowpipe, copper pipes and many kinds of sheet-copper structures can be fused together as one pipe, where brazing would otherwise be necessary.

A Parisian metallurgist claims to have perfected a process of welding copper to steel wire so as to make a non-corrosive coating. Many advantages, it is said, will result from the use of this new wire, such as high tensile strength and elasticity, combined with smaller surface exposed to wind and sleet than would be the case with iron wire at the same conductivity.

This wire, it is said, is especially useful over long spans, as pole intervals may be much greater where it is used. Compare with "Brazing," page 82.