Addnl. data considered in abstracting and indexing are available from a source cited in the original document. With a square-wave feed concn. variation, with a simple homogeneous or parallel reactions, a real advantage of periodic operation with a continuous stirred tank is not possible. With a higher order reaction, the ethanolamine-ethylene oxide reaction to form di- and triethanolamine, the selectivity and the space-time yield of the intermediate is strongly dependent on the frequency and unsymmetery of the input function. With appropriate concn. function, the selectivity for the intermediate product can be 37% higher than with steady operation. The space-time yield can increase 1.5% with a 17% increase of selectivity. [on SciFinder (R)]