Expansion of Air by Heat

Air, it is well known, will, when heated by one degree of Fahrenheit, expand about 1/480th part, and continue to expand so as to have its expansive force or tendency increased in about the same proportion for every additional degree of temperature.

Dalton determined that 100 parts of air, being heated from 55° to 212°, expanded to 132 5/10, parts; this gives us an expansion of 1/483 parts for 1° Fahr: Gay Lussac determined the expansion to be 1/480, and although, in Sir David
Brewster's edition of Robinson's philosophy, 24/10000, or about 1/417, is stated, we find Dr. Ure, in his “Dictionary of Arts” (article, "Expansion”), states that all gases expand 1/480 for each degree of Fahrenheit.

It follows that, if the temperature of a permanently elastic aeriform body be augmented by about 480°, the bulk of that body will be doubled, or, if it be retained within the space it originally occupied, its pressure will be doubled. It is by availing myself of this well known law of expansion by heat, and the new arrangement of particles in the close furnace, that I can obtain a rush of power from the furnace along the pipe C, analogous to the rush of steam from a steam-engine boiler along the steam-pipe to the engine,— equal to it in pressure, power, and constancy, and, when required, at much greater velocity.

The air driven into A for the support of combustion must, of course, be driven in against the pressure due to the heat of the products of combustion; for, supposing the latter are at the temperature of about 500°, there will be an atmosphere of surplus pressure against the blower; and it will be found that the blower, to do its work, will require half the power generated by the heat.