Hydrolysis of Starch Grains by Polarized Infra-Red Radiation

AT the Liverpool meeting of the British Association in 1923, it was shown that polarized radiation had the effect of accelerating the change of starch grains, in a weak suspension of diastase and at ordinary laboratory temperature, into a crystalline reducing substance ; but if the diastase were active or concentrated, no selective effect was observed1. Earlier experiments in 1922 had shown me that, when ground cereals in plain tap water were exposed to this radiation, a portion of the starch was turned to sugar. This was estimated by Bertrand's method2. To meet criticism that the effect might be due to the pressure of the cover glass, the experiment was repeated ; but instead of using a microscope slide, the starch suspension was in a flat-bottomed, very thin-walled flask, the base of which was irradiated by light, polarized and reflected vertically upward by a suspension of diastase in an outer vessel3.