It is true that on the Greek, Etruscan, and Roman pottery a subdued and hardly apparent glazing was applied to the surface of the pieces, but it is so slight as to leave a barely appreciable effect upon the eye, beyond that which might be produced by a mechanical polish, and so thinly laid on as almost to defy attempts at proving its nature by chemical investigation; it is, however, supposed to have been produced by a dilute aluminous soda glass, without any trace of lead in its composition, the greater portion of which was absorbed into the substance of the piece, thereby increasing its hardness and leaving only a faint polish on the surface of the ware. In Egypt and the east the use of a distinct glaze (_invetriatura_ of the Italians), covering the otherwise more porous substance of the vessel, appears to have been known and to have arrived at great perfection at a very remote period. It was in fact a superior ware, equivalent to the porcelain of our days, and from the technical excellence of some of the smaller pieces has been frequently, but wrongly, so called. It will perhaps be as well, before entering further into the consideration of the subject, to define and arrange the objects of our attention under general heads. Pottery (_Fayence_, _Terraglia_), as distinct from porcelain, is formed of potter’s clay mixed with marl of argillaceous and calcareous nature, and sand, variously proportioned, and may be classed under two divisions: Soft (_Fayence à pâte tendre_), and Hard (_Fayence à pâte dure_), according to the nature of the composition or the degree of heat under which it has been fired in the kiln. What is known generally in England as earthenware is soft, while stone ware, queen’s ware, &c. are hard. The characteristics of the soft wares are a paste, or body, which may be scratched with a knife or file, and fusibility, generally, at the heat of a porcelain furnace. These soft wares may be again divided into four subdivisions: unglazed, lustrous, glazed, and enamelled. Among the three first of these subdivisions may be arranged almost all the ancient pottery of Egypt, Greece, Etruria, and Rome; as also the larger portion of that in general use among all nations during mediæval and modern times. We shall be occupied with the glazed and enamelled wares: the first of which may be again divided into siliceous or glass glazed, and plumbeous or lead glazed.