Abstract: A bath for producing deposits of gold by electrodeposition, comprising: an aqueous solution containing at least one soluble gold cyanide compound; formic acid in a concentration of at least 20 ml/l to about 150 ml/l of said bath solution, said formic acid concentrations being calculated on a 90% by weight grade of formic acid; a cobalt compound; sufficient alkali to bring the pH to within the range of 3.5 to 4.4; and as conductivity salts and inhibitors, malic acid or a combination thereof with gluconic acid or with a water soluble organophosphorus chelating agent, said conductivity salts and inhibitors being present in at least sufficient quantity to provide a specific gravity of at least 13 Baume' in said bath.

Abstract: An electroplating apparatus for high-speed electroplating a cathodic strip of metal passed therethrough. The apparatus includes an elongated cell subdivided into a plurality of sub-cells defined by bottom and side walls and slotted partition walls for passage of the strip from one sub-cell to the next. Each sub-cell is provided with a pair of anodes, and means are provided for circulating electrolyte continuously in and through each sub-cell. The elongated cell is mounted within a surrounding sump tank which functions to collect and remove the overflowing electrolyte. The anode pairs present in each sub-cell are preferably activated in time sequence, proceeding from one end to the other of the cell.

Abstract: Gold plating baths comprising a nickel or cobalt brightener/hardener, containing oxalic acid and additionally at least one dicarboxylic acid selected from the group consisting of succinic acid, malonic acid, glutaric acid and adipic acid, enable the use of low current densities with improved efficiencies in producing bright deposits; also enable bright deposits to be obtained at high temperatures of about 150.degree. F.

Abstract: Gold plating baths comprising a nickel or cobalt brightener/hardener, containing a dicarboxylic acid having the formula HOOC--(CH.sub.2).sub.n --COOH in which n is an integer from 1 to 4 and mixtures thereof, an acid selected from the group consisting of malic acid, gluconic acid and formic acid and mixtures thereof, plus optionally oxalic acid, enable the use of high current densities with attainment of improved efficiencies in producing bright deposits; also enable bright deposits to be obtained at high temperatures of about 150.degree. F.

Abstract: In the electrodeposition of gold by electrolyzing an aqueous solution containing potassium gold cyanide, the improvement which comprises including in the solution a critical concentration of formic acid, a phosphonic acid type chelating agent and a cobalt or nickel compound, at a critical pH, to achieve extremely rapid plating speeds. Relatively high plating temperatures in the range of about 90.degree. to 160.degree. F. and high current densities ranging up to about 1000 ASF may be used to achieve fast plating speeds without degradation of the quality of the deposit.

Abstract: Apparatus is disclosed for selectively electroplating continuous longitudinally extending stripes or lines onto continuous metal base strip.

Abstract: An electrolytic cell for recovering from electrolytes metals, the ionic species of which are present at relatively low concentration. The cell comprises a container for the electrolyte, and and an electrode assembly in the container comprising (1) a tub-tubular sparger, having a central axial cavity bounded by an electrolyte-permeable cylindrical wall, and having an opening for receiving flow of the electrolyte into the central cavity and being otherwise closed, whereby the electrolyte flows radially from the sparger through the cylindrical wall; (2) a first electrolyte-permeable, high surface area electrode, coaxially surrounding the sparger to receive the flow therefrom; (3) an electrically insulating electrolyte-permeable spacer being coaxial with and surrounding the first electrode; and (4) a second electrolyte-permeable electrode being coaxial with the first electrode and contacting the insulating spacer at the side opposed to the first electrode, for receiving and passing the continuing radial flow.