nd to offer enough resistance to become heated, in the part selected, to an an- nealing temperature. In practice it is found necessary to keep the elec- trodes cool by keeping water circulat- ing in or around them. In order to prevent the plate cooling too rapidly after it has reached the proper… … bags of lump charcoal] placed on it. As soon as the coal becomes red hot a little more of the material is added, the operation being continued until the heated charcoal reaches up above the first draught hole. The door of the kiln is then plastered up, the stopping of the draught below preventing…
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