For producing the crayons by pressing, a simple apparatus is required. It consists of a horizontal metal cylinder with a well-fitting piston. The front of the cylinder is closed by a metal plate in which is an orifice of rather greater diameter than the crayons to be made. In front of the cylinder is an endless band which moves away from it. In using this apparatus to shape the crayons, the paste is made of such consistency that a slight pressure forces it out of the orifice in the front of the cylinder in a coherent rod. When the cylinder is filled with the paste, care must be taken that it includes no air bubbles, for these would cause the rod to break. The piston is then put in position and the mass forced by uniform gentle pressure out of the narrow opening. The endless band must move away at the same rate as the rod proceeds from the cylinder, so that a long stick of the crayon mass rests upon it. This stick is cut up by a blunt knife into uniform lengths, which are dried upon boards covered with blotting paper, and are then enclosed in casings similar to those of the ordinary lead pencil. The rods must be given a rather greater diameter than they are to possess when dry, since they shrink somewhat in drying. The second method consists in producing a thick paste which is moulded into blocks of the length of the crayons. These blocks are very slowly dried at a uniform temperature, and when completely dry, are cut by a fine saw into thin rods, which are then enclosed in a wooden case. The powder produced in sawing is used in the next operation. This simple process has many drawbacks. In the first place it is difficult in drying large blocks of the crayon mass to avoid cracks, which must be carefully filled with thin paste. Also in sawing up the blocks a large number of rods will be broken, even with the most careful treatment (these are again worked up with the powder produced in sawing). Thus, generally, the formation of crayons by pressure is preferred. It is important to dry the crayon rods so far that they do not shrink further after they are placed in the case; otherwise they would break up when sharpened. At times it is quite impossible to make a usable point on such a faulty crayon. =Crayons for Earthenware.=—Crayons for this purpose are made, according to M. Rösler, by finely powdering colours suitable for glass and earthenware, and mixing them to a paste with a solution of 2 parts of gum Arabic and 1 part of Marseilles soap. Pencils are then moulded from the paste and wrapped in a strip of paper just previously dipped in a paste of gypsum. Upon unglazed articles or ground glass these crayons can be used like a lead pencil. The colour is fixed by burning in the usual manner. CHAPTER LXVIII. CONFECTIONERY COLOURS.