1. A GAS FRACTIONATING APPARATUS CO-ACTING WITH A THERMAL SINK COMPRISING AN INSULATED COLUMN HAVING A BOILER IN THE BOTTOM THEREOF, SAID THERMAL SINK BEING ADAPTED TO CARRY OFF VAPOR FROM SAID COLUMN AND CONDENSE THE SAME, A DISTRIBUTOR FOR CONDENSATE RETURNING TO SAID COLUMN, CONDUIT MEANS IN THE INSULATED PORTION OF SAID COLUMN CONNECTING SAID THERMAL SINK TO THE UPPER PART OF SAID COLUMN, SAID CONDUIT MEANS COMMUNICATING WITH SAID DISTRIBUTOR FOR THE CONDENSATE RETURNING TO SAID COLUMN AND A VAPOR LIFT PUMP IN THE INSULATED PORTION OF SAID COLUMN OPERATIVELY CONNECTED TO SAID DISTRIBUTOR, A HEAT CONDUCTIVE MEMBER IN SAID COLUMN HAVING AN EXTERNAL SOURCE OF APPLIED HEAT AND BEING IN HEAT CONDUCTING RELATIONSHIP WITH SAID VAPOR LIFT PUMP, SAID RETURNING CONDENSATE BEING CONDUCTED TO THE LOWER END OF SAID VAPOR LIFT PUMP WHEREBY SAID CONDENSATE IS CAUSED TO RISE THEREIN DUE TO SAID SOURCE OF APPLIED HEAT UNTIL IT SPILLS INTO SAID COLUMN, A PORTION OF SAID HEAT CONDUCTIVE MEMBER BEING ADAPTED TO ASSUME A TEMPERATURE HIGHER THAN THAT OF SAID CONDENSATE, A CONTROL ELEMENT IN SAID BOILER FOR AUTOMATICALLY CONTROLLING THE LEVEL OF LIQUID IN THE BOILER BEING REDUCED IN CROSS-SECTION AT THE END CLOSEST TO THE BOTTOM OF SAID BOILER, SAID HEAT CONDUCTIVE MEMBER BEING OPERATIVELY CONNECTED TO SAID ELEMENT, SAID CONTROL ELEMENT BEING IN HEAT EXCHANGING CONTACT WITH THE LIQUID IN SAID BOILER, AND SAID REDUCED END OF THE CONTROL ELEMENT BEING SO SHAPED AND PROPORTIONED THAT THE THERMAL RESISTANCE OF THE ELEMENT VARIES AT DIFFERENT DISTANCES BETWEEN THE JUNCTION OF THE ELEMENT WITH THE HEAT CONDUCTIVE MEMBER AND THE LIQUID LEVEL INSIDE SAID BOILER.