WHEN AN ANALYTE IS QUANTIFIED by measuring the volume (or, on rare occasions, the weight) of a solution that reacts with it, we call the process volumetric analysis or titrimetry. Generally, the reaction in question proceeds to its equilibrium point or to some reproducibly measurable point near equilibrium, whereupon the addition of reactant solution (titrant) is halted and the amount consumed up to that point is recorded. The reactant endpoint may be indicated by the appearance or disappearance of a color or a precipitate or by a change in instrumentally measured potential or pH or some other property. The titrant may be added manually from a buret, or the whole process may be under closed-loop control with an automatic titrator.