The mixed process employed in Cumberland of roasting the ore, and afterwards smelting it in a small furnace resembling that called the Scotch, apparently yields a little less lead than if both operations were executed in the reverberatory furnace; but according to Mr. Forster, (see his Treatise on a Section of the Strata from Newcastle upon Tyne, &c.) this slight loss is more than compensated by the smaller consumption of fuel, the increased rapidity of the operation, and especially by the much greater purity of the lead obtained from the Scotch furnace. When it comes to be refined, the loss is only about one-twelfth or one-thirteenth, whereas the lead revived in the reverberatory furnace, loses frequently a ninth. Moreover, the lead furnished by the first method admits of being refined with profit, when it yields only 5 ounces of silver per fodder of 20 quintals, poids de marc, while that produced by the reverberatory furnace cannot be cupelled unless it gives 10 ounces per fodder; and as in the English cupellation, lead is constantly added anew without skimming, the litharge obtained in the second case can never be brought into the market, whereas the litharge of the leads from the Scotch furnace is of good quality. See the new method of enriching lead for cupellation, under [Silver].

As the smelting of galena, the principal ore of lead, is not a little complex, the following tabular view of the different processes may prove acceptable to the metallurgist:—

Treatment of Process of
I. Class.
Treated in reverberatory furnaces.		- A
De-sulphuration by roasting.		- 1. Pure ores -Pesey, Spain, &c.
2. Ores mixed with saline gangues. -England, in general.
3. Ores mixed with earthy gangues. -Viconago in Italy, and Redruth in Cornwall.
4. Ores mixed with several sulphurets. -Combined with the above.
5. Ores with earthy saline, and sulphurous gangues.
B
De-sulphuration by iron.		- 6. Ores with mattes, as at Vienne, in Dauphiny. -Vienne, Poullaouen, and Tarnowitz.
II. Class.
Treated in the mill-slag-hearth, the fourneau à manche, or Scotch furnace.		- A
Founding after roasting in a heap, or in a reverberatory.		- 7. Ores producing slags of various silicates.- Mattes, with raw lead. -Many places.
Workable lead, without mattes. -Villefort.
8. Ores producing compound silicate slags.- Mattes and workable lead. -Several places.
Workable lead. -Pont Gibaud and Scotch furnace.
B
Founding with direct desulphuration by metallic iron.		- 9. Ores producing slags composed of silicates and subsilicates.- Mattes and workable lead. -Baad-Ems, Hartz, Tarnowitz.
- Poor mattes and workable lead. -Tarnowitz.

The annual production of lead in Europe may be estimated at about 80,000 tons; of which four-sevenths are produced in England, two-sevenths in Spain, the remainder in Germany and Russia. France does not produce more than one five-hundredth part of the whole; and only one-fiftieth of its consumption.

See [Litharge], [Minium, or Red Lead], [Solder], [Sugar or Acetate of Lead], [Type Metal], and [White Lead].

LEAD-SHOT; (Plomb de chasse, Fr.; Schrot, Flintenschrot, Germ.) The origin of most of the imperfections in the manufacture of lead-shot is the too rapid cooling of the spherules by their being dropped too hot into the water, whereby their surfaces form a solid crust, while their interior remains fluid, and in its subsequent concretion, shrinks, so as to produce the irregularities of the shot.

The patent shot towers originally constructed in England obviate this evil by exposing the fused spherules after they pass through the cullender, to a large body of air during their descent into the water tub placed on the ground. The greatest erection of this kind is probably at Villach in Carinthia, being 240 Vienna, or 249 English feet high.

The quantity of arsenic added to the mass of melted lead, varies according to the quality of this metal; the harder and less ductile the lead is, the more arsenic must be added. About 3 pounds of either white arsenic or orpiment is enough for one thousand parts of soft lead, and about 8 for the coarser kinds. The latter are employed preferably for shot, as they are cheaper and answer sufficiently well. The arsenical alloy is made either by introducing some of this substance at each melting; or by making a quantity of the compound considerably stronger at once, and adding a certain portion of this to each charge of lead. If the particles of the shot appear lens-shaped, it is a proof that the proportion of arsenic has been too great; but if they are flattened upon one side, if they are hollowed in their middle, called cupping by the workman, or drag with a tail behind them, the proportion of arsenic is too small.

The following is the process prescribed by the patentees, Ackerman and Martin. Melt a ton of soft lead, and sprinkle round its sides in the iron pot, about two shovelfuls of wood ashes, taking care to leave the centre clear; then put into the middle about 40 pounds of arsenic to form a rich alloy with the lead. Cover the pot with an iron lid, and lute the joints quickly with loam or mortar to confine the arsenical vapours, keeping up a moderate fire to maintain the mixture fluid for three or four hours; after which skim carefully, and run the alloy into moulds to form ingots or pigs. The composition thus made is to be put in the proportion of one pig or ingot into 1000 pounds of melted ordinary lead. When the whole is well combined, take a perforated skimmer and let a few drops of it fall from some height into a tub of water. If they do not appear globular, some more arsenical alloy must be added.

Lead which contains a good deal of pewter or tin must be rejected, because it tends to produce elongated drops or tails.