The Production of Electrolytic Copper

Abstract

IN a note on the production of electrolytic copper, on p. 371 of NATURE of February 15, it is stated that “Mr. S. Cowper-Coles has hit upon anew plan, in which the copper is deposited on a vertical mandril, which is caused to rotate at a very rapid rate..... As a consequence, a smooth and dense deposit has been obtained with current densities approaching 200 ampères per square foot.” In reference to this I should like to point out that the idea of rotating the kathode with a view to obtaining greater rates of disposition is an old one. We have had in use at the Owens College for the last seven years a copper depositing tank in which the kathode consists of a vertical mandril 9 inches long and 3 inches diameter kept in rapid rotation, and capable of receiving a good copper deposit with a current of 100 ampères. The arrangement was devised by Mr. Henry Wilde, F.R.S., to illustrate the working of his patent, No. 4515, of 1875, and differs little from that used by Mr. Cowper-Coles. The mandril is driven from above, so that a stuffing-box in the bottom of the tank is unnecessary.