From observations on large, single, liquid crystals it has been found that nematic $p$-azoxyanisole exists in two distinct forms: One rotates the plane of polarization of transmitted light clockwise and the other, counterclockwise by the same amount, in analogy to the right- and left-handed forms of quartz, revealing a significant feature of the structure of nematic liquids which has not previously been reported.

• Received 7 June 1968

DOI:https://doi.org/10.1103/PhysRevLett.21.342