The Law of Volumetric Analysis states that any method of quantitative chemical analysis in which the amount of a substance is determined by measuring the volume that it occupies or, in broader usage, the volume of a second substance that combines with the first in known proportions, more correctly called titrimetric analysis. In volumetric analysis, the volume occupied by the concerned component is measured. Titration, a volumetric method, uses a solution of known concentration which is known as the titrating agent. This solution reacts in a certain manner with the component that is being analyzed. Titrations usually use visual indicators wherein the mixture changes colour. Sometimes the reactant is so strongly coloured that they serve as an indicator. However when a titrate reduces, it turns colourless.