What importance the question of optical activity of the lactic acid may assume is not definitely known.
The water used must be either distilled water or clear water which has been found to have no optical activity.
The lyotrope series also influence the optical activity of gelatine sols and the double refraction of strained gels.
optical activity n.
The property of an asymmetrical molecule in solution to rotate the plane of polarized light either clockwise or counterclockwise.