Rapid freezing apparatus

A portable self-contained apparatus for rapidly cooling samples comprising:

• an exterior housing having a peripheral side wall with an inner wall and an outer wall closed off at the top by an insulated cover and at the bottom by an insulated bottom wall having an opening therethrough;
• a cooling chamber having a peripheral side wall with an inner wall and an outer wall and an interconnected bottom wall mounted interiorly of said housing open at the top thereof, said open top of said cooling chamber being closed off by said cover;
• a flexible collapsible cloth bag mounted in said housing having a flexible and collapsible peripheral side wall mounted between the outer wall of the side wall of said cooling chamber and the inner wall of said housing with insulating means between the peripheral side wall of said bag and the inner wall of said housing, said bag having an insulated generally rigid bottom wall with an exterior wall and an interior wall closing off the bottom thereof disposed between the bottom wall of said cooling chamber and the bottom wall of said housing;
• normally closed valve means fluidly communicating the exterior wall of the bottom wall of said bag with the interior wall thereof thereby providing fluid communication through said valve means between the exterior or said housing via the opening in said housing bottom wall and the area between said bag bottom wall and said cooling chamber;
• and
• resilient means mounted in said housing disposed between the exterior wall of said bag bottom wall and said housing bottom wall normally biasing said bag bottom wall toward said cooling chamber whereby, when carbon dioxide is introduced through said valve means into the area between said bag bottom wall and said cooling chamber, said bag bottom wall moves downwardly away from said cooling chamber against the bias of said resilient means thereby indicating that the area between said bag and said cooling chamber is filled with carbon dioxide.