Examples of various developments are shown which have led to the present balances used for application in controlled atmospheres. The development started from the beam balance and the spring balance. The geometrical configuration, selection of materials and choice of indication resulted in a diversity of balances, adapted to physicochemical experiments in vacuo or in gases and vapours under predetermined temperatures and pressures. The introduction of feedback control, applicable to all basic modifications of mechanical balances, resulted in improved performance with reduced demands on mechanical design. It has facilitated the simultaneous observation of different variables, e.g. mass and torque or force components. The elements of automatic weight compensation in a closed loop are discussed. Feedback control represents the basis of free magnetic suspension which enables the weighing of an object in a closed container with an external balance and the measuring of forces on a body in controlled motion. It also enables signals for sample temperature and gas pressure to be transmitted through the wall of the reaction chamber. New developments in this special field are briefly discussed.