Probably this may be accounted for by the fact that the method of running the furnace when raw ore is being smelted is rather different from that adopted when dealing with roasted ore. Moreover, at the works under notice the furnaces are not of the most modern construction; and, as the old custom of dropping a peat in front of the blast every time the fire is made up still survives, it is necessary to shut off the blast while this is being done, and the fire is then apt to get rather slack. The gray slag produced in the hearth is smelted in a small blast furnace, a little poor fume, and sometimes a small quantity of fluorspar, being added to facilitate the process. Some figures regarding slag-smelting may be of interest. The slag-smelters produce 9000 lb. of lead in 24 hours. The cost of slag-smelting per ton of lead produced is as follows: Smelters’ wages $1.60 Coke (1500 lb.) 3.42 Peat 0.06 ———-- Total $5.08 Recent analyses of Weardale (Durham county) lead smelted in the Scotch hearth, and slag-lead smelted in the blast furnace, are given herewith: ─────────┬───────────────────┬────────────────────┬────────────────── │ FUME-LEAD FROM │ SILVER-LEAD FROM │ SLAG-LEAD FROM │ HEARTH │ HEARTH │ BLAST FURNACE ─────────┼───────────────────┼────────────────────┼────────────────── Lead │ 99.957 │ 99.957 │ 99.013 Silver │ 0.0035 │ 0.0200 │ 0.0142 │ (1oz. 2dwt. 21gr. │ (6oz. 10dwt. 16gr. │(4oz. 12dwt. 18gr. │ per Long Ton) │ per Long Ton) │ per Long Ton) Tin │ nil │ nil │ nil Antimony │ nil │ nil │ 0.874 Copper │ nil │ nil │ 0.024 Iron │ 0.019 │ 0.019 │ 0.023 Zinc │ nil │ nil │ nil │ ──────── │ ──────── │ ──────── │ 99.9795 │ 99.9960 │ 99.9482 ─────────┴───────────────────┴────────────────────┴────────────────── The ordinary form of the Scotch hearth is probably too well known to need much description. The dimensions which have been found most suitable are as follows: Front to back, 21 in.; width, 27 in.; depth of hearth, 8 to 12 in. Formerly the distance from front to back was 24 in., but this was found too much for the blast and for the men.