| Roasters’ wages | $2.08 |
| Roasters’ coal (1450 lb.) | 2.18 |
| Smelters’ wages | 2.04 |
| Smelters’ coal (600 lb.) | 0.92 |
| Peat and lime | 0.08 |
| Total | $7.30 |
In this case, as in that of ore, the smelter of the raw fume gets better pay; he has $1.44 per eight-hour shift, while the smelter of the roasted ore has only $1.02 per eight-hour shift.
Fume takes four hours to roast, as compared to the two hours taken by ore.
From these facts regarding Scotch-hearth smelting, it would seem that with galena carrying, say, over 70 per cent. lead (but more especially with ore up to 80 per cent. in lead, and, moreover, fairly free from impurities detrimental to “free” smelting), very satisfactory results can be obtained by smelting raw. Against this, however, it must be said that at the works where the ore is roasted attempts at smelting raw have been made several times without sufficient success to justify the adoption of this method, although the ores smelted average 75 per cent. lead and seem quite suitable for the purpose.
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 Hearth | Silver-Lead from Hearth | Slag-Lead from Blast Furnace | |
|---|---|---|---|
| Lead | 99.957 | 99.957 | 99.013 |
| Silver | 0.0035 | 0.0200 | 0.0142 |
| (1 oz. 2 dwt. 21 gr. per Long Ton) | (6 oz. 10 dwt. 16 gr. per Long Ton) | (4 oz. 12 dwt. 18 gr. 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 |