The salt-glazed ware is one of the hardest wares known, and is almost a porcelain in composition. The glaze gives a slightly uneven surface to the ware, which comes from the manner in which the wares receive the glaze. The pieces are not dipped in a glaze mixture, but when the kiln has reached a very high temperature common salt is thrown into the kiln; the soda is liberated from the salt by the action of the heat, and coming in contact with the silica of the stoneware clay, forms with it a silicate of soda, which is really a glass glaze. The composition of the ware is, generally speaking, clay and fine sand. Astbury, the potter, in 1720 used what is considered the best composition—grey clay and ground flint instead of sand. The colour is drab, or sometimes has a dull cream-coloured covering. The colour of the old Staffordshire ware is drab, with small white applied ornaments that were previously cast from moulds of brass or stoneware. Coloured enamels have also been very much used for decorating later work. The ornaments are single roses, may blossoms, _fleur-de-lis_, spirals, small interlacings, birds, figures, straight or wavy lines, &c., all generally very sharp and clear cut (Figs. 74, 75). [Illustration: Fig. 74.—Jar, White Stoneware of Staffordshire. (S.K.M.)] The potter John Astbury worked for the Elers, and after finding out as many secrets as he could from them, he left them and started a pottery of his own in Staffordshire. He used a wider range of clays and colours than those used by the Elers, and had more variety also in the decoration of his ware, which consisted of such ornaments as harps, crowns, stags, lions, and heraldic designs. [Illustration: Fig. 75.—White Salt-glazed Ware of Staffordshire. (S.K.M.)] Brown stoneware was made at Nottingham during the whole of the eighteenth century, and was of a bright rich colour; the material was thin and well fabricated. Besides the ordinary shaped jugs, puzzle-jugs and mugs in the shape of bears with movable heads were made, that were used in the beerhouses of the last century. Bristol and Liverpool were famous for their delft-ware during the last century. Richard, Frank, and Joseph Flower are names of potters who had delft works in Bristol. In Liverpool bowls with pictures of ships, arms, and landscape decoration were made of delft. Tiles on which were printed transfer decorations were also made of Liverpool delft by Sadler and Green, the inventors. These tiles were about five inches square, were printed in black or red, and were used for lining stoves and fireplaces. Theatrical characters and portraits of celebrities were the usual subjects. Wedgwood and other Staffordshire potteries sent their wares to Liverpool to get transfers printed on them.