_Shaft Furnaces._—The finished product from the Huntington-Heberlein blast-converters is of a porous character, and already contains a part of the flux materials (such as limestone, silica and iron) which are required for the shaft-furnace charge. It is just these two characteristics of the roasted product (its porous nature, on the one hand, leading to its more perfect reduction by the furnace gases; and, on the other hand, the admixture of fluxes in the molten condition, resulting in a more complete utilization of the temperature), which, together with its higher lead and lower zinc content, determine its ready fusibility. If we further consider that it is possible in the new process to make the total charge of the shaft furnace richer in lead than formerly (two-thirds of the total charge as against one-third), and that a higher blast pressure can be used without danger, it follows immediately that the capacity of a shaft furnace is much greater by the new process than by the old method of working. The daily production of the shaft furnaces on the old and the new process is as shown in the table given herewith: ─────────────┬─────────────────────────┬─────────┬──────────────────── │ │ CHARGE │ WORK-LEAD TYPE OF SHAFT│ CHARACTER OF CHARGE │ PER DAY,│ PRODUCED FURNACE │ │ TONS │ PER DAY, TONS ─────────────┼─────────────────────────┼─────────┼──────────────────── 3 tuyeres │{ Gray slag from } │ 36 │ 6 to 7 } │{ reverberatory } │ │ } │{ furnaces and } │ │ } Low- │{ sintered concentrate } │ │ }pressure │ │ │ } Blast 8 tuyeres │ ” ” │ 36 to 38│ 6 to 8 } │ │ │ } 3 tuyeres │{ Roasted product of } │ 36 │ 11 to 12 } │{ Huntington-Heberlein } │ │ │{ process } │ │ │ │ │ 8 tuyeres │ ” ” │ 65 to 72│ 24 to 26 } High- │ │ │ }pressure 15 tuyeres │ ” ” │ 270 │ 90 to 100 } Blast ─────────────┴─────────────────────────┴─────────┴──────────────────── It should be noted that the figure given for the furnace with 15 tuyeres represents the average for 1904; this average is lowered by the circumstance that during this period there was frequently a deficiency of roasted material, and the furnace had to work with low-pressure blast. A truer impression can be gained from the month of March, 1905, for instance, during which time this furnace worked under normal conditions; the results are as follows: