GAS, CALORIC, AND OTHER THERMO-DYNAMIC MOTORS.
Gas Motors.—Before the invention of the steam-engine Papin experi mented with the gases of gunpowder as a motive substance (see p. 244), and it will be readily understood that after the invention of the applica tion of steam the employment of other vapors than those of water, and of other gases than these of gunpowder, would suggest itself. This idea has been maintained up to the present time, and periodical efforts are made toward its realization.
In 1791, John Barber took out a patent for a rotary reaction sphere, like that of Hero of Alexandria (see p. 24o), into which, from a retort fur nace, also patented, there was to be introduced gas (evolved from wood, coal, or other hydrocarbons) which by burning, expanding, and escaping would cause the sphere to rotate. Three years later (over a hundred years after Papin's experiment with Guericke's cylinder, and after Newcomen's machine had been working for eighty years) Street patented a machine, consisting essentially of a Guericke and Papin cylinder, in which, instead of steam, there was to be used an explosive mixture of carburetted hydro gen-gas and air. In 1799, Lebon invented a machine, like a double-acting steam-engine, in which a mixture of gas and air was ignited by au electric spark. In 1823, Brown patented the application of the vacuum produced by the contraction of the exploded gas instead of by its direct action; he also patented an arrangement for cooling the cylinder by water. To ignite the explosive mixture, Wellinann Wright in 1833 used a gas-flame instead of the electric spark. His machine was direct and double-acting, the air and gas being forced in by two pumps and the proportion of the mix ture being regulated by the working of the machine itself through a ball governor. The flame-igniting system most widely used at present was invented by Barnett in 1838; he also invented the compression system so largely used. His first engine, which acted upon the up-stroke only, required a pump to take out the exhaust gases. Newton in 1855 ignited the gases by a piece of red-hot metal when the piston left uncovered a recess in which this piece of metal was placed. Barsanti and Alattetteci produced in 1857 an engine having a free piston in a long vertical cylinder, the explosion giving the piston considerable velocity, which, on the down-stroke only, was imparted to the fly-wheel. But it was
not until 1858 that the illuminating-gas motor of Degrand and lIngon, fol lowed in 186o by that of Lenoir, gave practical gas-engines. The efforts of Otto and other inventors placed these motors in competition with the steam-engine, as they could be employed where a great amount of power was not required or was needed only intermittently, or where the pres ence of the steam-boiler or the necessity for a skilled attendant was objectionable. In impelling its piston, the gas-engine or gas motor uses the force produced by the combustion of solid, liquid, or gaseous fuel in or with atmospheric air, the greater volume of the gaseous products of combustion, as compared with that of the substance burned and the air with which it combines, being due partly to purely chemical change of condition and partly to the heat of combustion.
Lenoir's (p1. ro6, fig. 1) has essentially the construction of a horizontal double-acting high-pressure steam-engine. There is a Ruhmkorff electric apparatus, from which wires run into the cylinder, and after the crank leaves the dead centre at each rotation there passes between the wires a spark which explodes the mixture of gas and air. There are four gas-passages and two valves, for admission and exhaust, while a jacket for water circulation keeps the cylinder comparatively cold.
The of 1864, shown in Figure 2, consists of a vertical cylinder, which supports the wheel and shaft and is surrounded for about one-half its height by a water-jacket. In its interior arrange ments it is much like the Papin apparatus (p. 8o, fig. 7), whose action it resembles in that an ignited mixture of gas and air forces the unloaded piston upward in the cylinder, which is open on top, and by its subsequent contraction permits the pressure of the atmosphere to do the actual work of driving-stile fly-wheel, there being a rack on the piston-rod, working in a pinion, and a ratchet motion which allows the piston and the rack to overrun the pinion during the explosion and to take hold of it on the down-stroke. In the Otto-Langen engine the explosions are utilized, in the Hugon and in the Lenoir they are absorbed, by dead masses. In the Otto-Langen machine the gases are ignited by a gas-flame.