Abstract: A device for handling and washing beads. The device is attachable to a test tube rack and includes a frame, a containing slide, and a capture slide. By manipulating the slides in various combinations of positions the beads may be added to, removed from, or separately washed apart from test tubes in the rack. Complete and easy washing of the beads may thus be accomplished.

Abstract: A sample holder and shutter assembly for photometers is disclosed in which a stationary sample chamber body is mounted in close proximity to a photosensitive device. A light path is provided from the sample chamber to the photosensitive device and shutter means is provided for selectively interrupting and opening the light path between the photosensitive device and the sample chamber without moving the sample chamber. Heat exchange means including a heat pump and a heat reservoir are provided for maintaining a desired temperature in the sample chamber. The sample chamber body is thermally connected to said heat pump and is preferably thermally isolated from the means mounting it. In one embodiment, the heat pump and heat reservoir are flexibly connected.

Abstract: A heat exchanger comprising:(a) a housing having an interior surface;(b) a thermally conductive member in intimate contact with the housing;(c) a thermally conductive element coaxially disposed in said housing and having an inner and an outer surface and in thermal communication with the member, wherein the inner surface of the element defines a first fluid passage, and wherein the interior surface of the housing and the outer surface of the element are in spaced relationship thereby defining a second fluid passage, the first and second fluid passages being in fluid communication;(d) a first port for maintaining the first fluid passage in fluid communication with a first external fluid;(e) a second port for maintaining the second fluid passage in fluid communication with a second external fluid; and(f) means for regulating the member's temperature; wherein heat is transferred between the member and the element via solid conduction.