Abstract: An improved limit switch mechanism is provided in which it includes a plurality of cassettes of limit switch subassembly, each cassette containing: a limit switch mounting bracket, a first limit switch and a second limit switch fastened onto said limit switch mounting bracket by screws; the deflection direction of the control lever of each limit switch being directed radially towards the center of the concerned switch actuator when each cassette of limit switch subassembly is inserted and fixed in a pair of slits, which is inclined at certain angle relative to horizontal direction and provided on opposite side walls of the base frame. Accordingly, positive actuation on control lever of each limit switch and long service life of each limit switch can be achieved.

Abstract: An extraction apparatus for extraction analysis of solid material is described, which consists of an extraction column mounted on a frame and a tubular filter holder mounted on the frame beneath the column. The holder is movable in the frame into and out of engagement with the lower end of the column.A multi-port valve is connectable to the lower end of the holder for supply of extraction liquid and flushing liquid to the column through the filter and for withdrawal of extraction liquid and flushing liquid from the column through the filter. The filter holder is removable from the frame for analysis of the solid material remaining after the extraction.