It is well known that the microscopist can readily distinguish potato starch from all other starches by the size of the grains. Saare has found that the size of the potato starch granules increases with the quality of the starch. In first quality starch they have an average diameter of 33 micro-millimeters, in second grade 21, in third grade 17, in the rinsing water 12, and in that floated off on the water only 8 micro-millimeters. Saare's paper may be found in full in the Zeitschrift fur Spiritusindustrie, vi., 482.