The plasticity of clay and its hardening qualities under the influence of intense heat, its adaptability to the most refined and appropriate forms, its affinity for the beautiful glazes and enamels so often associated with pottery, and its splendid traditions of craftsmanship, of colour, form and decorations, so beautiful and varied in character,--all combine to invest the subject with a charm or fascination of its own. Intrinsically valueless in its natural state, it is capable of being rendered almost priceless by scientific workmanship and artistic skill. The history of this material, and of its easy adaptation to the most refined and intricate, as well as the simplest of forms, affords invaluable lessons for present day artistic students. Pottery clay may be classified under three divisions or headings: (1) EARTHENWARE. (2) STONEWARE. (3) PORCELAIN. Under the first are grouped the largest number of Ceramic Wares. The pottery of Egypt, the faience of Assyria and Persia, the Greek and Etruscan vases, the famous red ware from the Isle of Samoa, and its counterpart the Roman Samian ware, the beautiful maiolica of Spain and Italy, the pottery of Rouen, St. Porchaire, Delft, and most of our English pottery are earthenwares; the paste or body consists of natural clays selected for their plasticity, their hardening qualities, their fusibility or their colour, and when burnt have a porous opaque body, usually dull in colour. This dulness was usually overcome by coating the ware with a slip of fine white clay, which, whilst not possessing inherent qualities to form pottery by itself, would adhere to the coarser coloured body of the earthenware, thereby forming a smooth white ground. The early Greek vases of Nancrates, the later Lekythos of the Greeks, the faience of Persia, the Mezza Maiolica and the Sgraffito of the early Italian Renascence, and our English slip ware are examples of this method of giving a smooth white surface to coarse coloured earthenware. A similar result to the slip covering was also produced by the use of a silicious glaze, rendered white and opaque by the addition of oxide of tin. Early Assyrian faience, Della Robbia ware, the Maiolica of Spain and Italy, and the wares of Delft and Rouen are earthenwares coated with a tin enamel. The silicious glaze here referred to is prepared by fusing silicious materials with soda or potash, and is known as Vitreous, or glass glaze. Plumbeous, or lead glaze, is produced by the addition of oxide of lead to the silicious glaze, rendering it more fusible, and still transparent. A white opaque enamel formed by using oxide of tin with the vitreous glaze, is termed Stanniferous, or tin enamel. These different processes of covering the porous body of the earthenware largely influenced the decorations and scheme of colouring.