Improvements in or relating to electrolytic ttreatment of metal foil

923,783. Treating metal foil or wire electrolytically. PLESSEY CO. Ltd. May 2, 1960 [May 4, 1959], No. 15194/59. Class 41. A method of electrolytically treating, e.g. etching, a continuous length of metal wire or foil 7, e.g. of aluminium, comprises supplying electric current to the wire 7 in a second bath 4, additional to the treatment bath 3 and insulated therefrom electrically by means including an insulating liquid layer 5, an electrode, e.g. the bath receptacle 2, being in contact with the liquid 4 and being spaced from the wire 7. The electric circuit is from a rectifier 14, receptacle 2, liquid 4, e.g. dilute HNO 3 , wire 7, liquid 3 and conductive receptacle 1, terminals R, S being connected across an A.C. supply. The baths 3, 4 are separated, as shown, by an insulating liquid 5, e.g. water, which may flow continuously between inlet 15 and overflow 16, the wire 7 passing through the liquid 5. Alternatively, the wire may be passed out through the upper surface of the bath 4 and subsequently enter the upper surface of the bath 3, and in this case the liquid 5 may be one of lower density than the liquids 3, 4, and float on the surfaces thereof. The bath 4 may provide the rectifying properties required, e.g. by employing a 5% sodium phosphate solution as the bath 4. The level of the liquid 5 may be higher than that of the liquids 3, 4 to prevent leakage of liquids 3, 4 into the bath 5.