New forms of instruments for showing the presence and amount of combustible gas in the air . verswho have proposed formulas for expressing the observed most generally accepted formulas are those due to Langmuir4and to In Fig. 4 are plotted the observed average heat loss per centi-meter from , 14, and 31 cm lengths of wire C and an 11 cmlength of wire A. As checks upon these observations the heat 8 Langmuir. Jour. Amer. Chem. Soc. 28, p. 1357, 1906. 6 Ann. Phys., 13, p. 582. * Physical Review, 34, p. 401. Weaver!Weibel J Combustible Gas Detectors 59 loss from the larger w
New forms of instruments for showing the presence and amount of combustible gas in the air . verswho have proposed formulas for expressing the observed most generally accepted formulas are those due to Langmuir4and to In Fig. 4 are plotted the observed average heat loss per centi-meter from , 14, and 31 cm lengths of wire C and an 11 cmlength of wire A. As checks upon these observations the heat 8 Langmuir. Jour. Amer. Chem. Soc. 28, p. 1357, 1906. 6 Ann. Phys., 13, p. 582. * Physical Review, 34, p. 401. Weaver!Weibel J Combustible Gas Detectors 59 loss from the larger wire calculated from Lorenzs formula, andthe heat loss for both wires calculated from Langmuirs formulaare plotted. The constants in the Lorenz formula were cal-culated from the observed heat loss at 4000 C. In calculatingfor both curves the heat loss due to radiation, the values used forthe emissivity of platinum at various temperatures were takenfrom Langmuirs paper. The observed heat loss for the larger wire lies between thevalues calculated from the formulas of Lorenz and of ao« i4oe TEMPERATURE OF WIRE (DEGREES CENTIGRADE) Fig. 4.—Loss of heat from wires in air Curves in order from top represent: (i) Observed loss from 14 cm length of mm wire; (2) loss frominfinite length of same wire calculated from Langmuirs equation; (3) observed loss from 14 and 31 cmlengths of same wire; (4) loss from infinite length of same wire calculated from Lorenzs equation; (5) lossfrom infinite length of mm wire calculated from Langmuirs equation; (6) observed loss from wire. It is apparent that for reasonable lengths of wire the differencebetween the observed average heat loss at a given temperatureand the true heat loss is negligible for our purposes. The distribution of heat due to combustion is probably nearlythe same as that due to the electrical current. If this is true,no serious error due to lead conduction is involved in the valuesfor power from combust
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