Air per pound of carbon................................ 17-1/8 lb. Time of experiment..................................... 4 h. 12 min. Water evaporated from 60 deg. into steam at 53 lb. pressure 1,620 lb. Heat lost by radiation and convection.................. 70,430 units. Mean temperature of chimney............................ 700 deg. F. " " " air................................ 70 deg. F. No combustible gas was found in the chimney. I will apply Carnot's doctrine to this case. Potential energy of the fuel with respect to absolute zero: Units. 239.25 lb. x 530 deg. abs. x 0.238 ...................... = 30,053 194.46 lb. x 17-1/8 x 530 deg. x 0.238, the weight and heat of air....................... 420,660 194.46 x 14,544 units heat of combustion of carbon... 2,828,200 --------- Total energy 3,278,813 Heat absorbed in evaporating 26.08 lb. of water in fuel............................................ -29,888 --------- Available energy.......................... 3,248,425 Temperature of furnace-- The whole of the fuel was heated up, but the heat absorbed in the evaporation of the water lowered the temperature of the furnace, and must be deducted from the heat of combustion. Units. Heat of combustion................................... 2,828,200 " " evaporation of 26.08 lb. water............... -29,888 --------- Available heat of combustion.............. 2,798,312 Dividing by 238.25 lb. gives the heat per 1 lb. of fuel used................................... = 11,745 units. And temperature of furnace: 11,745 units/(18.125 lb. x 0.238) + 530 deg.......... = 3,253 deg. Temperature of chimney 700 deg. + 460 deg................ = 1,160 deg. Maximum duty (3,253 deg. - 1,160 deg.)/3,253 deg............. = 0.643 deg. Work of displacing atmosphere by smoke at 700 deg.: Cubic feet. Volumes of gases at 70 deg......................... = 228.3 " " " " 700 deg......................... = 499.8 ----- Increase of volume.................... 271.5