. Transactions. o heat and kept 25° F. abovethe chosen temperature for 2 hr. before the heat was placed in furnace was provided with a door at each end, and at theproper time the large plate containing the 250 pots was drawninto the furnace. The furnace-temperature was then main-tained constant for 10 hr. Two pyrometer-couples, used for 374 COMMERCIAL CARBONIZING-MATERIALS. measuring the temperature, were counected to a recording-instrument, which gave a record of each couple every 40 the end of an hour, the first row of pots was drawn from thefurnace. The operation of drawing th
. Transactions. o heat and kept 25° F. abovethe chosen temperature for 2 hr. before the heat was placed in furnace was provided with a door at each end, and at theproper time the large plate containing the 250 pots was drawninto the furnace. The furnace-temperature was then main-tained constant for 10 hr. Two pyrometer-couples, used for 374 COMMERCIAL CARBONIZING-MATERIALS. measuring the temperature, were counected to a recording-instrument, which gave a record of each couple every 40 the end of an hour, the first row of pots was drawn from thefurnace. The operation of drawing this strip of sheet-iron uponwhich the pots were placed occupied about 30 sec. At the endof 2 hr., the next row was drawn, etc. The mass of the brick-work in the furnace used was sufliciently great to prevent suddenchanges of temperature. After the pots were cool, the piecesof steel were taken from them, carefully washed and were then sawn in two, polished, etched, and examinedunder the Fig. 1.—A Carbonizing Pot. Cross-Section. By the use of a micrometer eye-piece, the carbonized surfacewas measured. First, tiie depth of the zone of carbon contain-ing more than the eutectic ratio (which was considered as cent.) was measured, next the zone containing the eutecticratio. The remainder of the carbonization was then dividedinto two zones, the line of division being estimated as the pointwhich contained per cent, of carbon. The percentage ofcarbon in the extreme outer surface was also estimated. The COMMERCIAL CARBONIZING-xMATERIALS. 375 results of these measurements, weights, and estimations aregiven in Tables VII. to XXXI. Materials X and Y caused a decided pitting of the surface ofthe steel, and in many cases it was impossible to weigh thepieces accurately. The results regarding the depths of carbonization and in-crease in weight, shown graphically iu the diagrams of TablesVn. to XXXI., are designated by the letter corresponding tothe mate
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
