This invention significantly reduces the frequency of hydraulic failure in the analytical line of a capsule chemistry sample liquid analysis system which can occur when the reagents required for the specific analytical test have an imperfect merger with the sample aliquot reagent in the vanish zone of the analytical line. It has been found that the dynamic surface tension of the sample aliquot reagent and the analytical reagent influence the merging process. It has also been found that optimum merging of these reagent capsules in the vanish zone can be obtained when the dynamic surface tension of the sample aliquot reagent and analytical reagent is different.