ation of the charge, rather than to those in which the motor is an elastic vapor under pressure.
Frot's ammonia-engine resembles the steam-engine so closely that comparative experiments with the vapor of water and of ammonia have been made with it. See ammoniacal engine.
R. Waller (English patent, No. 1019 of 1854) uses condensible and permanent gases; as carbonic acid, ether, air. Vaporizes by steam or hot water.
Arbos (English patent, 3108 of 1862), steam and gas combined.
N. H. Barbour (No. 46,769, March 14, 1865) has a traveling car with reservoir supplied with carbonic acid from condensing stations along the route.
See compressed air-engines on this principle; Bompas and others, pp. 602 – 604.
In Delaporte's ammoniacal gas-engine, a is the boiler, d the cylinder, and b the tube communicating between the cylinder and the boiler.
c is the valve-box, and x the slider by means of which the gas is introduced alternately above and below the piston.
e is the eduction-
in the form of a scroll and united by a solder of pure tin run in between the layers.
（Mathews's patent.) Tanks made of a single thickness 1/16 inch of sheet-steel, lapped four inches at the edge, and soldered in this way, may be trusted to sustain a pressure of 300 pounds to the inch, the bursting pressure being 700 lbs. One of the thicker kind above mentioned, tested by hydraulic pressure at the Newport torpedostation, withstood strains up to 3,132 lbs. per square inch before rupture.
Barbour, March 14, 1865.
The car carries a supply of liquid carbonic-acid stored in a tank beneath.
This is admitted in regulated quantities to the cylinder, where it expands, and after doing its work, the gas is exhausted into a reservoir over the car, having a capacity 450 times that of the tank in which it is contained in the liquid state.
It is recondensed by appropriate machinery at the stations, and again used.
Smith, August 8, 1871.
Compressed air, contained in a large tank on the bod