Abstract: In this chromatograph for pressure chromatography, a plunger having a plunger stem is arranged so that it can move within the separation column (3). On the front face of the plunger there is a collecting space (7) for liquid, which is covered by a frit (6) and which has a connecting line (8) to the face of the plunger opposed to the front face. In order to prevent abrasive and chemical attack by the column packing on the plunger, its seal and the cylinder wall of the separation column, the plunger should comprise a lower part (2) having a device (4) to accommodate the plunger stem (5), and an upper part (1), the two parts being arranged so that they can move in relation to one another. The upper part (1) has a centering peg (9) which projects into the lower part (2). A spring (12) on which the upper part (1) is supported, is located concentrically in relation to the peg (9).

Abstract: An arrangement for surface treating workpieces has a pair of rotary conveyors each rotatable about a respective vertical rotation axis and provided with a plurality of angularly spaced holders each of which can grip a respective workpiece and advance it angularly stepwise through a plurality of respective working stations. In addition each of these holders can be rotated about an axis generally radial of the respective rotation axis for the rotary conveyor for treatment on all sides of each workpiece as it is stepped through the various surface treatment stations. A line conveyor extends tangentially passed the two conveyors and is of the walking-beam type. This line conveyor feeds workpieces to the upstream conveyor so that they then move around the working stations of this upstream rotary conveyor, then takes them off the upstream rotary conveyor and feeds them to the downstream rotary conveyor where they are stepped through the respective working stations of this conveyor.