514,693. Polyhydric alcohols. HELLICAR, A. G., TAYLOR, A. W. C., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. May 11, 1938, No. 14116. [Class 2 (iii)] Polyhydric alcohols are prepared by the hydrogenation of an aqueous mixture containing hydroxy - aldehydes and hydroxy - ketones resulting from the condensation of formaldehyde in aqueous medium and containing residual formaldehyde by subjecting the mixture to the action of hydrogen in the presence of a hydrogenating catalyst and maintaining the pH of the reaction mixture (as measured at atmospheric pressure and a temperature of 20‹C.) within the limits 6.5-10 and preferably within the limits 7-9 by adding to the reaction mixture a substance or substances having an alkaline reaction. Suitable alkaline substances are potassium hydroxide, sodium hydroxide, calcium carbonate, magnesium oxide or magnesium carbonate or non-volatile organic nitrogen bases, e.g., triethylanine,ethanolamines or pyridine or the salts of a weak base with a strong acid, e.g., sodium formate, sodium acetate or disodium orthophosphate. Nickel is preferably used as the hydrogenation catalyst and the hydrogenation may be carried out under increased pressure at an elevated temperature. In the examples a solution prepared by the condensation of formaldehyde in aqueous medium according to the process described in Specification 513,708, is hydrogenated in the presence of magnesium oxide or sodium hydroxide and a nickel catalyst, on kieselguhr as a carrier.