Measurement of Crystal Growth of α-Lactose

A method is described to measure growth rates of the individual faces of tomahawk-shaped a-lactose crystals. Results show good reproducibility and good lincarity with time. They prove, together with growth studies of broken crystals, that the lactose crystal grows only in one direction of its principM axis and, therefore, has its nucleus in the apex of the tomahawk. Growth rates increase with a power of the supersaturation greater than unity, which power is different for different faces, thus altering the shape of the crystals.