Note 21 — Chapter IX · COMPOUNDS OF CARBON WITH OXYGEN AND NITROGEN
George Kamensky translation
If in manufactories it is necessary, for instance, to maintain the temperature in a furnace at 1,000°, the flame passes out at this or a higher temperature, and therefore much fuel is lost in the smoke. For the draught of the chimney a temperature of 100° to 150° is sufficient, and therefore the remaining heat ought to be utilised. For this purpose the flues are carried under boilers or other heating apparatus. The preparatory heating of the air is the best means of utilisation when a high temperature is desired (see Note 22).