blast furnace manager, however, will have observed that, even with every precaution in the blast furnace practice, pig iron will often be obtained with so high a percentage of sulphur as to render it useless for the Bessemer acid or basic processes.  If the desulphurization in the blast furnace is carried sufficiently far, it is always necessary to work the furnace hot, and thus to obtain hotter iron than is desirable for further treatment in the converter.  On the other hand, the method of further desulphurization outside the blast furnace, described in this paper, presents the double advantage that part of the blast furnace can be kept cooler, and thus lime and coke be saved, and that there is a certainty that no red-short charges are obtained in the treatment in the converter, while the pig iron passes to the converter at a suitable temperature.

[Illustration:  FIGS. 1 through 5]

A further advantage presented by the direct process described in this paper is that the Bessemer works is independent of the time at which the individual blast furnaces are tapped, as the pig iron required for the Bessemer process can be taken at any moment from the desulphurizing plant.  In Hoerde, where the mixing and desulphurizing process has for a considerable time been regularly in use, it has been found that all the chief difficulties formerly encountered in the method of taking the fluid pig iron direct from the various blast furnaces to the converter have been obviated.  At Hoerde the mixing and desulphurizing plant shown in the accompanying engravings is employed.  This apparatus holds 70 tons of pig iron.  It is, however, advisable to have an apparatus of greater capacity, say 120 tons.  The apparatus has the shape of a converter, and the hydraulic machinery by which it is moved is simple and effective.  An hydraulic pressure of eight atmospheres is sufficient to set it in motion.  The vessel is provided with a double lining of firebricks of the same quality as those used for the lining of blast furnaces.  This lining is gradually attacked only along the slag line, and does not require repair until it has been in use for some six weeks.  Further repairs are then necessary every three weeks.  Only the few courses of spoilt bricks are renewed, and for the repairs, including the cooling of the vessel, a period of two or three days is required.  At the end of the week the vessel is kept filled, so that its contents suffice for the last charge to be blown on Saturday.  On Sunday night the vessel is again filled.  The consumption of manganese is very low; theoretically, it is the quantity required for the formation of manganese sulphide, and in practice it has been found that this amounts to about 0.2 per cent.  The proportion of manganese which the desulphurized pig iron coming from the vessel should contain is best kept at about 1.5 per cent. in order to render the desulphurization as complete as possible.  Thus, a mean proportion of 1.7 per cent. of manganese