A Compact Co2 Chilling Device for Continuous Duty in Paraffin-Type Sectioning

To obtain uniform sections cut from some of the newer embedding materials of lower melting points, particularly the polyethylene glycols, it is necessary to cool the microtome knife. A cooling device constructed for this and other paraffin-type sectioning consists of a small brass wedge attached to the knife by means of an adjustable spring clip. The wedge is small enough to mount directly on the back of the knife and does not interfere with any movement of the microtome. Three small channels are drilled in the wedge to provide one entrance and two exits for gaseous CO₂. CO₂ from an upright tank is regulated by a modified Spencer Model 930 freezing attachment, which is connected to the brass wedge by copper capillary tubing.