At the middle of the Eighteenth Dynasty glass first appears, and of the reigns of the Amenheteps III and IV a number of seals have been found of a beautiful semitransparent deep blue glass. Of the late Eighteenth Dynasty a few specimens are known of cyanus, an alkaline silicate coloured a deep blue with carbonate of copper, and this material was used in increasing quantity till the Twenty-sixth Dynasty. [Sidenote: Schist and steatite.] Besides the hard stones enumerated above, shelly-limestone, schist, and steatite were also employed, and a few scarabs are known that were made of ivory. Steatite (or soapstone) was used in the manufacture of scarabs from the Twelfth to the Twentieth Dynasties, and by far the greater number of specimens are made of this material. It is a silicate of magnesium, soft, easily cut, and at the same time its superior compactness secures it from being readily broken or injured, and it is also capable of receiving a higher finish and much sharper impression of the subject than porcelain. [Sidenote: The Glazes.] The steatite scarabs were nearly always glazed, and the glazing often helps to indicate the date of a specimen. Only by a careful study of a large number of specimens can the eye be accustomed to differentiate between the varieties of glazing used at different periods. A very fine blue glaze of excellent quality is characteristic of the Twelfth Dynasty, and green glaze was also often used at this period. Many shades of blue and green glaze of very hard quality are found on the specimens of the Thirteenth Dynasty, and the few Hyksos scarabs that yet retain their colour show that a green glaze of a poorer quality was used at that period. The characteristic glazes of the early Eighteenth Dynasty are green, of a slightly greyish tint, generally of a fine surface, while those of the latter half of the dynasty, though coarser in quality, are often very brilliant in colour, and show a variety of tints ranging through all the shades of blue and green. Violet glaze was also employed at this period. The glazes of the Nineteenth Dynasty are often poor in quality, and generally of a dark yellowish-green colour, though sometimes blue and violet. The colour commonest during the Twentieth and later period are blue of various shades. It should be remarked here that the greatest number of scarabs are brown or white: the brown ones were invariably coloured green, and the white specimens blue. 4. MISCELLANEOUS FORMS OF SEALS. [Sidenote: Miscellaneous forms.] Besides scarabaei, other forms of seals are met with in Egypt. Many of them have little models of men or animals on the back, as human-heads, symbolic eyes, hippopotami, lions, hedgehogs, ducks, fish, frogs, flies, crocodiles; while not a few are shaped like cowries.