Désiré Jean Baptiste Gernez: Metastable saturation, crystallization, and triboluminiscence

Resumen

Desiré Gernez was a prolific French physicist and chemist that studied the phenomenon of rotatory power of substances in different states of aggregation. He found that this property was a molecular phenomenon and that the liquid molecules vaporized without a change in structure. He also found that many substances having no optical activity (i.e. amides and certain salts) were able to change the rotatory power of tartaric and malic acids. Gernez studied in detail the physics of the metastable states of supersaturation of salt and gases and the sub-cooling and superheating of liquids. He found more than 30 salts that showed the phenomenon of supersaturation. He proved that addition of microcrystals of the solute, or its isomorphs, were enough to cause the crystallization of a supersaturated solution. Likewise, a supersaturated solution of a racemate could be separated into each enantiomer, depending on the nucleus used to convert it into a saturated one. His experiments showed that bodies that caused the crystallization of a supersaturated solution lost this ability when they were washed with tap water and dried in flask containing sulfuric acid. He found that solids disengaged gases because their surface was always covered with roughness forming a network of capillary conduits into which the gases could penetrate and condense. He also determined the absorption spectra of a variety of substances, among them chlorine, iodine chloride, sulfur, selenium and tellurium and their halides, and alizarin. The spectra of colored vapors were better observed with a spectroscope of several prisms, while colored liquids were better-observed using spectroscope of one prism.