The art of welding copper was well known to the ancients; but the secret by which two pieces of copper can be joined so as to present as perfect a union as that made in welding iron was by some accident lost, and many millions have since been spent in resuscitating it from oblivion. The lost-art is stated to have been at last rediscovered by James .Burns, of Pittsburg. The economic value of the process lies in the fact that, even by the best methods now known to metallurgists, copper scrap cannot be economically utilised because of the difficulty in welding a mass of pieces into one body. Bums recently demonstrated before a critical audience that his process is not a mere sham. After flattening a rod of copper 3/8 in diameter, he formed a disconnected ring. The usual "scarfing " process - forming a union by means of an oblique joint - followed; and then the operator, after sprinkling a certain powder over the piece, proceeded to make a weld which, when cooled, showed a perfect union. He next took the ring, which measured 2 in. diameter, and submitted it to a strain until its longest width had been extended 3/4 in., its shorter width being narrowed to a corresponding degree, a circle being thus changed into an ellipsis.

This was a more severe test than iron is expected to stand, and demonstrated conclusively that the union of the two ends of the rod was not the mere " brazing " of the coppersmith.

Burns's discovery opens up a new field in working copper, and will in all probability cause great changes in some lines of manufacture. At present, to make a copper ring for fitting over a joint, or making a gasket or joint, it had to be cut round out of a solid plate, causing great waste. To repair broken or defective pipes, brass had to be used; and should an intense heat strike the brazed part afterwards, the brass would melt and ruin the piece. But by the Burns process the economic use of copper is assured, and copper scrap, now worth but one-third its weight of new copper, would be as high in value as ingot copper. It is said that the ingredients which form the powder used by Burns in welding are very cheap. - (Chambers's Journal.)