the multiples may be 2 3 or 4 resulting in an inflatable bag 21 having a volume of for example 16 glove volumes the glove volume may be simply determined by filling the glove 13 with water weighing the filled glove 13 and dividing by the weight per unit volume of water it may be noted that twice the glove volume is the maximum sudden change in pressure for which the unit may be called upon to compensate the value of the weight 27 is selected to maintain a constant steady state pressure in the glove box 11 such a pressure is typically relatively small on the order of a few ounces per square inch for example 0 1 to 1 psi pounds per square inch the value of the weight 27 may be simply calculated in a cylindrical embodiment by the relation that the area of the cross section of the cylinder divided into the sum of the weight of the cover 25 and the weight of the weight 27 is equal to the pressure per square inch applied upon the inflatable bag 21 thus for example if the pressure is 0 1 psi and the total weight of the cover 25 and the weight 27 equals one pound the area of the cylindrical cross section is 10 square inches fig2 illustrates an embodiment employing a purifier 31 to remove impurities in the air in the glove box 11 such a purifier 31 may be for example a furnace to remove oxygen or various well known filtering systems used for example in biological applications the embodiment of fig2 is structurally and functionally equivalent to that of fig1 with the exception of the insertion of the purifier 31.