Improvements in or relating to freeze-drying

1,062,031. Freeze drying. EDWARDS HIGH VACUUM INTERNATIONAL Ltd. April 3, 1964 [April 3, 1963], No. 13252/63. Heading F4G. In apparatus for freeze-drying samples of animal or vegetable tissue or the like, the sample is frozen and introduced into an evacuable chamber 1 in a cup 12, which contains wax or impregnant 18, sealing and evacuating the chamber, controlling the temperature of the sample by thermo-electric modules 10, 11, using the Peltier effect on which the cup is supported, the heating effect being utilized after completion of drying to polymerize, melt or thermally treat the wax or impregnant to embed or impregnate the sample whilst still under vacuum. The heat removed from the upper surface of module 11 in contact with the cup 12 is transferred to the lower surface of module 10 by the Peltier effect and is removed by cooling coils 7 connected to the base 2 of the chamber. The generated vapour may be removed by pumping or by desiccant 9 and a thermistor 15 controls power to the modules to maintain the temperature of the sample at any desired temperature.