Eligio Perucca

Eligio Perucca (28 March 1890 in Potenza – 5 January 1965 in Rome) was an Italian Physics instructor and researcher at the University of Turin in Italy in the early decades of the twentieth century. He later served a professorship at the nearby Polytechnic University of Turin. He discovered an important principle in stereochemistry in 1919, but his contribution was overlooked and forgotten until recently.

Perucca received a Ph.D. degree in Physics from the University of Pisa at the astoundingly young age of 20. He became Assistant to Professor Naccari in 1911 at the University of Turin, a post he retained for 11 years.

In 1922 Perucca succeeded Professor Majorana to the chair of Experimental Physics at the Polytechnic University of Turin. He retained that appointment until 1960. In addition he was Rector of the Polytechnic from 1947–1955, and largely devoted his energy to rebuilding the physical facilities which had been destroyed during World War II.

Upon arriving at the University of Turin, Perucca launched into the study of polarized light. In 1913 he invented a sensitive light meter known as the Bilamina de Bravais-Perucca, which is still highly regarded for its precision.

In a paper published in 1919, Perucca reported an experiment which produced optical rotatory dispersion (ORD) as a result of passing linearly polarized light through colored crystals of sodium chlorate. Perucca was attempting to replicate a nineteenth-century experiment (1860) in which amethyst exhibited optical activity in the visible light spectrum. He used a readily-available substitute for the amethyst. Sodium chlorate is chiral as a crystal, but in its natural (undyed) state is transparent and does not exhibit enhanced optical activity, so Perucca added an organic dye (an equilibrium racemic mixture of a triarylmethane textile dye then known as extra China blue). His goal was to see if addition of the organic dye on the crystalline structure would induce enhanced optical activity (rotation) of light in the 500-600 nm absorption band on the otherwise optically inactive dye.

...
Wikipedia