Optical cells which maintain both constant diameter and constant internal mass during pressurization also maintain constant molar cross section (moles/cm2). In the recent article of le Noble and Schlott, ‘‘All quartz optical cell of constant diameter for use in high pressure studies,’’ the authors erroneously assume that the diameter of their constant internal mass, syringe‐type cell is constant during pressurization [W. J. le Noble and R. Schlott, Rev. Sci. Instrum.47, 770–771 (1976)]. In contrast to the authors’ principal conclusion, cell corrections are required in using the cell of their design. The corrections required to compensate for pressure‐induced variations of molar cross section allow accurate employment of le Noble and Schlotts’ useful cell design.