Abstract
Of the two available methods for the determination of hydrogen-ion concentration, the electrometric is the more fundamental and satisfactory but it requires somewhat elaborate and expensive apparatus. The colorimetric method, on the other hand, though not lacking in difficulties if accurate results are wanted, requires no special apparatus and the actual procedure is simple. It is based on the electrometric method, and involves the use of buffer solutions of known hydrogen-ion concentration determined originally electrometrically.