[Letters to Editor]

THE fact that the molecular weight of a gas or vapour in ounces occupies 22.4 cub. ft. at S.T.P. seems to have been pointed out first by Prof. J. W. Richards in an article on ``Some Abridgments in Chemical Calculations'', published in the Journal of the Franklin Institute, 152, 109 (1901). It is quoted as far back as the 1912 edition of Dr. J. W. Mellor's ``Modern Inorganic Chemistry''.