Abstract: A housing having an inclined surface and a pair of footrests is provided. A plurality of impact rods are disposed in perpendicular to the inclined surface and axially slidably mounted in the housing. An impact head is secured to a top of each of the impact rods. A reciprocating device is provided for reciprocating the impact rods so as to impact a sole of a user mounted on the footrest. A reciprocating device and a drive motor for actuating the reciprocating device are disposed in a mass block that is suspended from the housing.

Abstract: To remove fluorides from a vapor generated by evaporation under reduced pressure of an aqueous solution of crude phosphoric acid containing fluorides, the vapor is at first brought into direct contact with cooling water to accomplish a partial condensation of the vapor and transfer the fluorides almost entirely to the condensate, and the noncondensed portion of the vapor is brought into direct contact with a separate cooling water. The mixture of the condensate and cooling water resulting from the partial condensation step is cooled by indirect heat exchange with a cooling fluid and partly recycled as cooling water to the partial condensation step.