Abstract: A method and apparatus (10) for delivering dry bulk material (21) to a drilling mud system (50) of an oil and gas well comprises a plurality of collapsible bags (30) for holding a quantity of dry bulk material (21), each bag (30) being supported on a bag storage rack (20) having a discharge outlet (22) connected to the bags (30), the discharge outlets (22) having bag discharge valves (24); a hopper (40) for receiving and collecting material from the bags (30) and for discharging material into the drilling mud system (50) by means of a hopper discharge valve (48); a length of material discharge hose (70) connected to the discharge outlets (22) and to the hopper (40); and a vacuum pump (60) having a vacuum hose (47) to the hopper (40) for producing a vacuum in the hopper (40) and the hose (70) and thereby drawing material (21) from the bags (30) into the hopper (40) for discharge into the mud system (50).