On consulting M. LEBON, he communicated to me the following observations: "You may have remarked," said he, "in sitting before a fire, that wood sometimes burns without flame, but with much smoke, and then you experience little heat, sometimes with flame, but with little smoke, and then you find much warmth. You may have remarked too, that ill-made charcoal emits smoke; it is, on that account, susceptible of flaming again; and the characteristic difference between wood and charcoal is, that the latter has lost, together with its smoke, the principle and aliment of flame, without which you obtain but little heat. Experience next informs us, that this portion of smoke, the aliment of flame, is not an oily vapour condensable by cooling, but a gas, a permanent air, which may be washed, purified, conducted, distributed, and afterwards turned into flame at any distance from the hearth. "It is almost needless," continued he, "to point out the formation of verdigrise, white lead, and a quantity of other operations, in which acetous acid is employed. I shall only remark that it is this pyroligneous acid which penetrates smoked meat and fish, that it has an effect on leather which it hardens, and that _thermolampes_ are likely to render tanning-mills unnecessary, by furnishing the tan without further trouble. But to return to the aëriform principle. "This aliment of flame is deprived of those humid vapours, so perceptible and so disagreeable to the organs of sight and smell. Purified to a perfect transparency, it floats in the state of cold air, and suffers itself to be directed by the smallest and most fragil pipes. Chimnies of an inch square, made in the thickness of the plaster of ceilings or walls, tubes even of gummed silk would answer this purpose. The end alone of the tube, which, by bringing the inflammable gas into contact with the atmospheric air, allows it to catch fire, and on which the flame reposes, ought to be of metal. "By a distribution so easy to be established, a single stove may supply the place of all the chimnies of a house. Every where inflammable air is ready to diffuse immediately heat and light of the most glowing or most mild nature, simultaneously or separately, according to your wishes. In the twinkling of an eye, you may conduct the flame from one room to another; an advantage equally convenient and economical, and which can never be obtained with our common stoves and chimnies. No sparks, no charcoal, no soot, to trouble you; no ashes, no wood, to soil your apartments. By night, as well as by day, you can have a fire in your room, without a servant being obliged to look after it. Nothing in the _thermolampes_, not even the smallest portion of inflammable air, can escape combustion; while in our chimnies, torrents evaporate, and even carry off with them the greater part of the heat produced.