John Bethell

“ So that, in a room filled with twenty persons and lighted by four oil lamps, as much as 360 cubic feet of air per hour is rendered not only unfit for respiration, but absolutely poisonous. The air thus heated rises to the upper part or ceiling of the room, and would escape if there were any outlet for it. But in most of our private dwellings there are none to be found. ”

“ The mechanical arrangement by which the light is produced consists of a series of concentric rings, perforated on the upper surface for the escape of the gas, placed at equal distances from each other, and so arranged as to regulate the quantity of atmospheric air, and to communicate by conduction and radiation sufficient heat to raise the temperature of the gas to a given point, so as to effect the separation of its charcoal immediately on its leaving the burner, and then, by an arrangement above, to bring fresh atmospheric air to the proper points of the flame. ”

“ A perfect lamp will deposit the charcoal in the flame the instant it passes the jet. If so imperfect as to deposit too soon, charcoal will be found in the rings; if too late, then high up in the flame. There is a point of accuracy required which practice has determined. This mechanical arrangement brings about a series of chemical changes involved in the evolution of light and heat which are very interesting. The rapidity of chemical union governs the respective quantities of heat and light. By a too rapid combination, heat without light may be produced. ”