. A treatise on steel : comprising its theory, metallurgy, properties, practical working, and use. order to extract all the clay which has been impreg-nated with the oil used for smearing the spindle andthe plug. Next, a small lump of clay, placed at theend of a stick, is pressed into the opening, and the CAST STEEL, 177 whole firmly united with another piece of wood,similar in shape to the bottom of the crucible. The pot, with the bottom hole closed, and the topbent as we have said, has the appearance shown inthe next figure. The next operation is to extract itfrom the mould. To do this, the
. A treatise on steel : comprising its theory, metallurgy, properties, practical working, and use. order to extract all the clay which has been impreg-nated with the oil used for smearing the spindle andthe plug. Next, a small lump of clay, placed at theend of a stick, is pressed into the opening, and the CAST STEEL, 177 whole firmly united with another piece of wood,similar in shape to the bottom of the crucible. The pot, with the bottom hole closed, and the topbent as we have said, has the appearance shown inthe next figure. The next operation is to extract itfrom the mould. To do this, the workman takes themould and carries it to another hole dug in the floor,in the centre of which is a vertical rod of iron, termi-nated by a flat head of metre diameter. This Fig. head passes through an aperture left at the bottomof the mould, and raises the movable bottom withthe pot on top, while the mould is lowered down thefloor hole. The workman then takes the pot, pullinggently to free it from any of the clay which has gotinto the centre hole, and carries it to the board,where it is left to dry awhile in the air. 178 TREATISE ON STEEL. 273. The drying is finished in a drying-room,where the temperature is kept at about 30° C. (86°F.), and lasts several days, until all moisture is ex-pelled. When the pots are to be used, they are putinto the smelting furnace, where the temperature isincreased gradually up to a cherry-red heat; at thispoint, they are ready to receive a charge. 274. The annealing of the pots presents great diffi-culties, and requires a great deal of care: the firemust be regular; a sudden increase will make themcrack; once properly heated, they will easily bearthe changes of heat and cold to which they are sub-jected. Plumbago crucibles, pa
Size: 1553px × 1610px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, bookidtreatiseonst, bookyear1868
