Abstract: The invention relates to a stabilized high voltage source the output voltage of which may be regulated in wide range, whereby the adjusted output current is constant at variable load. The high voltage supply source comprises a high voltage rectifier fed by a push-pull driving circuit, a control circuit supplying push-pull width modulated control signals of the driving circuit and an error signal processing circuit working up the divided voltage and current signals taken from the output of the high voltage source. The output signal of the error signal processing circuit is applied to the control circuit as a control signal. The supply voltage of auxiliary circuits of the supply source is provided by a stabilized low voltage supply unit.

Abstract: A process for the selective dissolution of molybdenum in the presence of tungsten in which the molybdenum is dissolved in an aqueous solution, having a pH of from -0.5 to +2.0, of a peroxy compound selected from the group consisting of hydrogen peroxide and ammonium peroxysulfate and in the presence of a catalyst selected from a salt of the group consisting of iron, nickel, copper, silver and thallium.