Abstract
The (001), (010) and (100) surfaces of Rochelle salt crystals are etched by lightly rubbing on filter papers moistened with distilled water, and the structure of etched surfaces and the light figures revealed are observed. The (001) surface is covered with etch pits of rectangular pyramids, some of them line-bottomed and some of them flat-bottomed, surrounded in each case by {027} and {105} facets. Similar etch pits appear on the (010) surface but they are formed of {190} and {0, 24, 1} facets. On the (100) surface, etch pits of a boat shape and of a shallow trough surrounded by {28, 0, 1}, {410} and {520} facets are observed, the last of which is sometimes {520}_??530, are observed. Corresponding to the etched structures, light figures of regular shapes are revealed by the (001), (010) and (100) surfaces, respectively, although they are somewhat indistinct.
