The authors determined active hydrogens of guanosine and yeast nucleic acid by the method proposed by Roger J. Williams which consists in dissolving the substances in deuterium oxide, evaporating to dryness and determining the increase in, weight due to the replacement of active hydrogen by deuterium. The experiment showed that the number of active hydrogen of guanosine was 6, corresponding to the theoretical number, while the tetrasodium salt of the yeast nucleic acid was found to have 11-12 active hydrogens.
Acknowledgment. We are greatly indebted to Prof. Titani for the kind supply of deuterium oxide. The work was aided by a grant from the Scientific Research Fund of the Department of Education.