METHOD AND APPARATUS FOR THE REMOVAL OF GAS FROM LIQUID, WHEREBY SUBSTANTIALLY ALL ABSORBED AND ENTRAINED GASES ARE LIBERATED AND ELIMINATED FROM HYDRAULIC SYSTEMS AND PREFERABLY CLOSED SYSTEMS AND THE LIKE; PROVIDING FOR THE CIRCULATION OF PRIMARY HYDRAULIC SYSTEM FLUID WITH COMPLEMENTARY HYDRAULIC SYSTEM FLUID, AND WITH THE PROVISION OF A SURFACE TENSION DEVICE THAT COLLECTS DIMENSIONALLY LARGE ENTRAINED GAS BUBBLES; PROVIDING FOR SEPARATION FROM CIRUCLATION OF A BODY OF FLUID TO BE BATCH PROCESSED AND REPLACED INTO CIRCULATION FOR COMMINGLING IN SAID PRIMARY-COMPLEMENTARY SYSTEMS, AND WITH THE PROVISION OF VACCUMIZATION AND SONIC ENERGY APPLICATION TO BE APPLIED TO SAID SEPARATED BATCH OF FLUID WHEREBY GAS LIBERATION THEREIN IS STIMULATED AND THE TIME REQUIRED THEREFOR REDUCED TO A PRACTICAL MINIMUM; AND PROVIDING FOR REPEATED BATCHING AND COMMINGLING UNTIL SATURATION BECOME INSIGNIFICANTLY SMALL AND ACCEPTABLE AS MAY BE PRESCRIBED.