The refractometric method is used to demonstrate hydrogen-bond complex formation between aromatic chloro-groups and the a-methene or -methylene groups of ester residues. The bond between chlorobenzene and ethyl acetate has an energy --3kcal./mole in aqueous ethanol. This type of bond probably assists the adsorption by cellulose acetates of dyes containing chloro-groups. Chlorobenzene is strongly adsorbed by cellulose triacetate, probably by this mechanism. The hypothesis of -C1. . . HCbonding may assist in the interpretation of the relative degrees of plant growth-hormonc activity of chlorinated aryloxyacetic acid derivatives.
IntroductionWhen calcium carbonate is calcined in lump form, as in industrial lime-burning practice, the decomposition occurs at an interface advancing inwards from the outside of each lump,' as often observed for other solids.2 A similar mode of decomposition was found for more finelydivided, i.e., precipitated, calcium carbonate, and the manner in which the surface activity and