Salts are obtained by combining an acid substance with a basic substance. Common salt, or table salt (NaCl, sodium chloride), was one of the most important chemical substances known in antiquity. Paracelsus (1493-1541) held that salt was the principle that imparted solidity to materials. He called "salt" any product of evaporation that was soluble, crystalline, and bitter-tasting. Some of these salts, such as Glauber's salt (sulfate of soda), proved to be of some value in iatrochemical terms, i.e., for medical chemistry.