A process and models of apparatus are described which provide for the preservation of biologics by desiccation in vacuo from the frozen state at greater convenience and lower cost of operation than heretofore. Water-vapor is removed by a specially prepared calcium sulfate which may be regenerated by heat at atmospheric pressure. Procedures for the desiccation of various types of substances are described.


“Cryochem” is derived from the Greek roots κρύος and χημια to denote desiccation in vacuo from the frozen state by means of chemicals. We have coined this word to designate our process in which calcium sulfate is used. If temperatures of −50°C. or lower are used for initial freezing, the final product is “lyophile” as defined by Reichel. If other means are used, such as self-freezing after degassing, as later described, the product may be termed “cryochemic.”

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