1. The theory of General Polarity has been applied to the effect of ionisable complexes on the rotatory power of optically active benzoates and holds for ortho,di-methylamino, hydroxy and carboxy esters.
2. The ortho amino ester is a notable exception, which has been explained in view of recent work by Sidgwick on co-ordination compounds, and confirmed by evidence of boiling points and solubilities.
3. The exceptionally high value for the union-ised ortho hydroxy ester has also been explained by Sidgwick's work.
4. The meta and para compounds are unaffected by ionisation except in the case of the hydroxy compounds,the changes in which are governed by the general polar effect.
5. The concentration of the solution has a very marked effect on the rotatory power of the ionised Sodium sec-β-octyl phthalate. A very rapid drop in rotation accompanied by an inversion in sign taking place as the concentration rises. No satisfactory explanation can be advanced to account for this peculiarity.