Plate glass is cast by pouring it from a large pot on to a flat iron table with a ridge all round it, and on which an iron roller is so placed that when the molten glass flows on the table it passes over and flattens it out to the required thinness, which is regulated by elevating or depressing the ridges at the sides of the table, made moveable for that purpose (the process is illustrated by the cut at the head of this article). When cold, the surface of the plate is ground perfectly flat and even by means of emery-powder (fig. 6), and then polished with a cloth rubber charged with a fine red oxide of iron called “crocus” (fig. 7). The grinding and polishing are both performed by steam machinery. Illustration: FIG. 7. (‡ POLISHING THE PLATE GLASS.) Illustration: FIG. 8. (‡ BLOWING GLASS INTO FORM.) Bottles, and such like articles are either simply blown into the form required, or into moulds made to close upon the ball of soft glass, and again open when the required form has been given (fig. 8). Many articles of glass are cast, or “struck-up” by compression in a mould, and are often made to resemble cut-glass articles, but they are much inferior in appearance. The best articles of glass are first blown, and afterwards cut and polished (see “Glass-cutting”). Of whatever kind the article of glass may be, it is so brittle that the slightest blow would break it, a bad quality which is got rid of by a process called “annealing.” This consists in placing it while quite hot on the floor of an oven, which is allowed to cool very gradually indeed. This slow cooling takes off the brittleness; and articles of glass well annealed, will scarcely break with boiling water, and are very much tougher than others. GLASS-CUTTING. Illustration: GLASS-CUTTING.