(1) A series of 1-menthyl n- alkyloxyacetates has been prepared which gives a decreasing molecular rotation - growing chain curve with a maximum at the butyloxy- and amyloxy- members. (2) A number of menthyl hydrogen esters of the dicarboxylic acids have also been prepared. Here a minimum probably exists at the 10th and 11th atoms from the asymmetric centre. The molecular rotatory powers both in the homogeneous state and in solution are of an alternating character, the odd members giving the higher values. (3) Alternation is destroyed when the sodi salts of these esters (2) are examined in aqueous solution. (4) In both series all members examined show normal and simple dispersion. (5) In addition, the influence of the o -sub: : etituents, Br, I and CH3, on the rotation of d- sec -f f octyl benzoate has been examined. Except for iodine these substituents have the same relative effect as in the substituted menthyl benzoates and in benezene substitution.