The
caloric theory is an
obsolete scientific theory that
heat consists of a self-repellent fluid called
caloric that flows from hotter bodies to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores in solids and liquids. The "caloric theory" was superseded by the mid-19th century in favor of the
mechanical theory of heat but nevertheless persisted in scientific literature until the end of the 19th century.