Removal, by suction, of anodic gases formed in electrolytic cells employed for aluminum production

Claim 1

IN A PROCESS OF MAKING ALUMINUM BY ELECTROLYTIC REDUCTION OF ALUMINUM OXIDE IN A MOLTEN SALT BATH, IN WHICH A CARBON ANODE SURFACE IS IMMERSED, GAS COMPRISING AN OXIDE OF CARBON FORMING IN SAID PROCESS, AND ALSO A CRUST OF SOLIDIFIED BATH FORMING ABOVE THE BATH, THE GAS COLLECTING IN A SPACE UNDER THE CRUST; THE IMPROVEMENT COMPRISING OSCILLATINGLY DRILLING A HOLE IN SAID CRUST AND APPLYING SUCTION DIRECTLY THROUGH SAID HOLE TO SAID SPACE SUFFICIENTLY TO LOWER THE PRESSURE AT SAID HOLE TO BELOW ATMOSPHERIC PRESSURE SO AS TO PREVENT FORMATION OF A CUSHION OF SAID GAS AGAINST AND BENEATH THE SURFACE OF SAID ANODE, WHILE THE ELECTROLYSIS IS GOING ON.