It has been found that free boric acid is without effect on the rotation of ethyl d-tartrate but alkali borates have a large effect, and it has been shown that boric acid unites with ethyl d-tartrate (dextrorotatory) to an exceedingly small degree, but borate ion combines with the diol, giving laevo-rotatory boro-diol complex, and with increase of the concentration of borate ion and with fall of temperature the complex formation advances. Thus it has been suggested that only borate ion combines with diol (polyvalent alcohol), but undissociable boric acid does not.
The molecular structures of fluorobenzene and o-difluorobenezene have been investigated by the electron diffraction method. The C-F distances in these molecules have been determined as 1.34±0.04 Å and 1.35±0.03 Å, respectively. These distances are shorter than expected from the covalent radii of Pauling and Huggins. This shortening has been discussed in terms of resonance among several valence-bond structures. The dipole moment of halogen-substituted benzenes has been considered in relation to the carbon-halogen distances and the double bond character of the linkage.