A device used in chemistry to compare the colors of solutions held in flat-bottomed tubes and viewed along the length of the tube. Often a solid glass plunger is moved along one of the tubes to effect a color match, the position of the plunger indicating the depth of color of the unknown solution. 2.
A photoelectric device used to compare and match an unknown color with a known color sample. In this process the two colors may be alternately placed in the position for measuring, or two identical measuring systems may be employed to feed a null indicator.