Abstract: A vibratory plating method carried out by placing only workpieces and a plating liquid in a plating container, and applying an electric current across the plating liquid while vibrating the plating container so as to cause the workpieces to be plated as the workpieces are rolled and moved independently of one another along the plating container. By this plating method, workpieces can be plated uniformly in a very short period of time at a high current density and with a small amount of plating liquid. Moreover, it eliminates troublesome steps of manually suspending and removing workpieces from hangers.

Abstract: A concurrent-biaxially drawn polyvinyl alcohol film is prepared by fabricating a molten hydrate polyvinyl alcohol into a film; drying it under preventing an orientation thereof to form a substantially non-orientated substrate film having a water content of 3 to 20 wt. %; coating an aqueous dispersion of a macromolecular compound on at least one surface of the substrate film to form a coated film having an average water content of 5 to 30 wt. % with an increased water content of 2 to 10 wt. %; concurrent-biaxially drawing the coated film at an area elongation percent of 600 to 1300% to form a drawn film; drying the drawn film under releasing stress at a water content of less than 3 wt. % to form a dried film; and heat-treating continuously the dried film at higher than 160.degree. C. and lower than a decomposition temperature for a short time.

Abstract: A vibratory plating apparatus having a plating liquid in a plating container, a base on which the container is mounted for vibrating movement, and a lid for the top of the container. The bottom of the container has an arcuate bottom. A vibration motor vibrates the container and electrodes are disposed within the container. With this plating apparatus, workpieces can be plated uniformly in a very short period of time at a high current density and with a small amount of plating liquid. Moreover, it eliminates troublesome steps of manually suspending and removing workpieces from hangers.

Abstract: A sludge containing a sparingly soluble metal compound such as nickel carbonate or the like is supplied to an anode compartment or an intermediate compartment of an electrolytic cell provided with an anode compartment and a cathode compartment or with an anode compartment, an intermediate compartment and a cathode compartment each sectioned by a filter membrane or an ion-exchange membrane, and thereafter an electrolytic treatment is conducted by using an insoluble electrode as anode and a usual electrode as cathode to precipitate a metal such as nickel on the cathode. Effective recovery of a metal is attained directly from a sludge by way of electrolysis.