SMOKE

, or Smoak, a humid matter exhaled in form of vapour by the action of heat, either external or internal; or Smoke consists of palpable particles, elevated by means of the rarefying heat, or by the force of the ascending current of air, from certain bodies exposed to heat; which particles vary much in their properties, according to the substances from which they are produced.

Sir Isaac Newton observes, that Smoke ascends in the chimney by the impulse of the air it floats in: for that air, being raresied by the heat of the fire underneath, has its specisic gravity diminished; and thus, being disposed to ascend itself, it carries up the Smoke along with it. The tail of a comet, the same author supposes, ascends from the nucleus after the same manner.

Smoke of fat unctuous woods, as fir, beech, &c, makes what is called lamp-black.

There are various inventions for preventing and curing smoky chimneys: as the æolipiles of Vitruvius, the ventiducts of Cardan, the windmills of Bernard, the capitals of Serlio, the little drums of Paduanus, and several artifices of De Lorme. See also the philosophical works of Dr. Franklin. Pans, resembling sugar pans, placed over the tops of chimneys, are useful to make them draw better; and the fire-grates called register-stoves, are always a sure remedy.

In the Philosophical Transactions is the description of an engine, invented by M. Dalesme, which consumes the Smoke of all sorts of wood so effectually, that the eye cannot discover it in the room, nor the nose distinguish the smell of it, though the fire be made in the middle of the room. It consists of several iron hoops, 4 or 5 inches in diameter, which shut into one another, and is placed on a trever.

The late invention called Argand's lamp, also consumes the Smoke, and gives a very strong light. Its principle is a thin broad cotton wick, rolled into the form of a hollow cylinder; the air passes up the hollow of it, and the Smoke is almost all consumed.

Smoke Jack, is a jack for turning a spit, turned by the Smoke of the kitchen fire, by means of thin iron sails set obliquely on an axis in the flue os the chimney. See Jack.