1,187,547. Syringes. INSTRUMENTATION SPECIALTIES CO. June 17, 1968 [Nov. 29, 1967], No. 28672/68. Heading F1R. [Also in Divisions G1 and G2] Apparatus for fractionating and transferring liquid from a density gradient tube 84, used in density gradient centrifugation, comprises a piston 40 fixed to a support arm 14 of a stand 10, and a tube support 70 which is axially movable relative to the piston 40 by a lead screw 54 rotated by a synchronous electric motor 64 and working in a half nut 56 fixed to stand arm 16, axial movement of tube 84 over piston 40 displacing the tube contents through piston passage 46 tapered opening 48 preventing turbulence. The tube contents pass through a chamber 20 having quartz windows 22 through which light from an ultra violet lamp 34 passes to an optical detector 36 comprising a filter and a photo-cell. As the optical characteristics of the liquid passing through chamber 20 vary, a varying output signal is produced by detector 36, and is recorded on a chart associated with a recorder 38. The axial position of tube 84 is indicated by a moving scale 76 sliding in an adjustable fixed scale 78. Tube 84 is returned to its lowermost position by loosening half nut 56, or by using a revercible motor.
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