1. AN APPARATUS FOR DRESSING CRUDE ASBESTOS SEPARATED FROM THE SOURCE ROCK AND BEING IN THE FORM OF FIBROUS BUNDLES SUSPENDED IN A LIQUID, COMPRISING A HOUSING, AN INLET ON SAID HOUSING FOR ADMITTING THE FIBER-LIQUID MIXTURE INTO SAID HOUSING, AN OUTLET ON SAID HOUSING FOR DISCHARGING THE FIBER-LIQUID MIXTURE FROM SAID HOUSING, A MOTOR-DRIVEN SHAFT ROTATABLY MOUNTED WITHIN SAID HOUSING, A RIGID WORKING SURFACE ON SAID SHAFT, A LINING OF ELASTICALLY YIELDING MATERIAL INFLATABLE WITH COMPRESSED AIR IN SAID HOUSING FIXEDLY HELD ON THE WALL OF SAID HOUSING AND CLOSELY ENGAGING SAID WORKING SURFACE ON SAID SHAFT WHEN IN FULLY INFLATED CONDITION, A REGULABLE FEED PUMP FOR FORCING WITH A CONTROLLABLE HYDRAULIC PRESSURE THE FIBER-LIQUID MIXTURE ADMITTED THROUGH SAID INLET INTO SAID HOUSING IN A CIRCULATING FLOW BETWEEN SAID RIGID WORKING SURFACE ON SAID SHAFT AND COUNTERFRICTION SURFACE OF SAID LINING WHILE SUBJECTING THE FIBERS TO FRICTION AND CONTINUOUSLY BENDING THEM IN CONSTANTLY VARYING DIRECTIONS, AND FOR CONVEYING THE FIBER-LIQUID MIXTURE TO SAID OUTLET ON SAID HOUSING, A COMPRESSED-AIR PIPE FOR SUBJECTING SAID LINING TO THE ACTION OF COMPRESSED AIR, AND A REGULATING MEMBER FITTED IN SAID COMPRESSED-AIR PIPE AND PERMITTING, WHEN OPERATED, THE BEARING PRESSURE OF SAID LINING SURROUNDING SAID WORKING SURFACE ON SAID SHAFT TO BE ADJUSTED TO THE FRICTIONAL EFFECT AND THE INTENSITY OF BENDING THE FIBERS WHICH RESULT IN COMPLETELY OPENING UP THE FIBERS.