Chemical engineering . eriment described the beginning of the run there were 55 volts between ter-minals Ti and T3; then the resistance of K was gradually de-creased by piling bricks on the granular carbon till hours,when tlie c. m. f. between a and b was 42 volts. No furtherchange was made till hours, when, after increasing theresistance of V, the e. m. f. between Ti and Ti was increasedto no volts. This increased the e. m. f. between a and b to 65volts, causing the temporary increase in resistance observed. In building this furnace the upper branch of the resistorw as 4 cm
Chemical engineering . eriment described the beginning of the run there were 55 volts between ter-minals Ti and T3; then the resistance of K was gradually de-creased by piling bricks on the granular carbon till hours,when tlie c. m. f. between a and b was 42 volts. No furtherchange was made till hours, when, after increasing theresistance of V, the e. m. f. between Ti and Ti was increasedto no volts. This increased the e. m. f. between a and b to 65volts, causing the temporary increase in resistance observed. In building this furnace the upper branch of the resistorw as 4 cms. thick; that is to say, it was made of the same thick- ness as the lower resistor, in spite of its being shorter and hav-ing a smaller heating surface. The obser\ations made in Msshowed that although the upper resistor was so thick the gen-eration of heat in the lower resistor was more rapid, for whenthe muffle first showed a red heat this was noticed in the bot-tom. This showed that the effect of the pressure of the. FIG. 7.—CURVES OF POWER AND RES1ST.\NCE. muffles on the lower branch of the resistor made the resistancelower than that of the upper branch. Although this uneven heating was observed, it was decidedbefore making any change to try another experiment, usingmore energy. The experiment was made on the day followingthe previous run, and the furnace started with a temperaturewell over 100° in .I/5. The results obtained arc shown by thecurves in Fig. 8. When silver melted in .U5 at hours, thepower was cut dow-n with the object of finding out whether,liaving reached this temperature, the furnace could be held atthat point with a much smaller consumption of energy. Itwas found, however, that the furnace cooled off rapidly, andalthough at the end of an hour M5 still showed a red heat, •3- \ - 1 0-^ i } fs > s V ?/ y i / v\ \, 8 \ / / ^ V 1 / \ r i 3/ V V 1 \ ( / v^ . , ( » \ \ \ 11 1 [ ; n 0 1 1 Ino^ ._ L_ 1_ _ _ _ FIG. 8.—CURVES OF POWER AND RESISTANC
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectmetallu, bookyear1902
