The partial order with respect to a given reactant can be evaluated by the method of flooding (or of isolation) of Ostwald. In this method, the concentration of one reactant is measured with all other reactants in large excess so that their concentration remains essentially constant. For a reaction  with rate law  the partial order  with respect to  is determined using a large excess of . In this case
 with 
and  may be determined by the integral method. The order  with respect to  under the same conditions (with  in excess) is determined by a series of similar experiments with a range of initial concentration  so that the variation of  can be measured.