An iron pan about one metre in diameter, with an iron cover furnished with a pipe opening into a flue, is used for melting the lead. This arrangement is designed to protect the workman from the dangerous vapours evolved from the molten metal. At the workman’s side of this cover is a counterpoised slide, which only remains open when the counterpoise is held in check by a lever. In front of the kettle there is an iron plate movable about a horizontal axis. The lead being heated to just above its melting point, the workman takes 7 to 8 kilogrammes of metal in a ladle, and pours it on the plate, which is horizontal. The lead solidifies in a very short time, but before it is completely solid the plate is inclined towards the pan so that the still liquid lead runs back into it, leaving a very thin sheet on the plate. The hard sheet is removed from the plate, and the latter cooled by cold water to be ready for a new casting. The sheets made in this way are not more than 1 to 2 millimetres thick. They are then cut into strips of a width to suit the size of the pots in which they are converted into white lead; the width of the sheets is generally 5 to 6 centimetres. Since the rate at which the white lead is formed depends on the surface of the metallic lead, instead of continuous sheets the lead is generally cast into gratings. For this purpose an iron plate, upon which are intersecting strips, is used instead of the flat plate. Plates for the casting are also used containing grooves intersecting at right angles. In the first case, plates are obtained in which are openings meeting at right angles, and in the second case, according to the distance of the grooves apart, a more or less wide-meshed lattice work. [Illustration: FIG. 4.] 2. =Building up the Stacks.=—The rolled-up lead plates are placed in the pots. These (Fig. 4) are somewhat conical in shape; they have at some distance from the bottom a projecting ring, or sometimes three projections only, upon which the lead spiral rests. Before the spirals are put in position, a quantity of ordinary vinegar, about a quarter of a litre, is poured in. There must be sufficient room below the spiral so that it shall not be in contact with the vinegar. The insides of the pots are glazed at least half-way up, so that the liquid does not penetrate the porous earthenware. The pots have a capacity of about 1 litre, and a diameter at the top of 10 centimetres. If lead plates are used, the pots are about 20 centimetres high; if gratings are used the pots may be lower, by which there is economy in room and a larger number can be placed in one stack. The stacks, built up of pots and manure, are of different sizes; it is not advisable to make them too small, or the loss of heat would be considerable. A stack 4 to 5 metres long, 3½ metres wide and 6 to 7 metres high will contain 6,000 to 8,000 pots and 9,000 to 11,000 kilogrammes of lead.