Lxxxix. the Hemicelluloses of the Wood of English Oak

PREVIOUS work [O'Dwyer, 1934] has shown that the hemicellulose A of oak wood is a mixed polysaccharide containing anhydroxylose and uronic anhydride units and that the sapwood product differs from that obtained from heartwood in that it gives with iodine the blue colour which is characteristic of starch. It has since been shown [O'Dwyer, 1937] that the blue colour reaction given by the sapwood product is accounted for by the presence of anhydroglucose units in the molecular structure and that glucose can be obtained therefrom quantitatively on hydrolysis with takadiastase under controlled conditions. The present communication records a further stage in the fractionation of hemicellulose A isolated from both sapwood and heartwood.