FIRE-EXTINGUISHER, or VIRK-ANNIIIII.A TOR. .1n apparatus by means of wide!' lire may he extimmished, usually by pouring on it water charged with some gas that is incapable of sup porting combustion, especially 1.arhonie acid gas (q.v•). An extinguisher of this eharaeter was originally brought into successful use in Lon dim in 1816, and a palent was applied for in the 'United States for a similar apparatus by William A. 1;T:1111am in 1837. These ex timmishcrs are of various forms and shapes, and consist for the most part of a convenient reservoir of water, within wide]] are two small vessels, one containing some carbonate, and the other a strong aeid. 1\ hen the apparatus is to he used the contents of the smaller vessels are emptied into the water; the variant dioxide liber ated from flue carbonate by the acid is then partly taken up by the water, and the pressure created by the eonfined gas forces out the solution in a strong jet when the vessel is opened. The Babcock extinguisher, which has been exten sively used in the I hilted States, consists of a cylindrical vessel which may be carried on the back, tilled with a solution of sodium bicarbonate, over which is suspended a vessel containing sulphuric acid. which is made to tilt over and discharge its contents into the solution when brought into use, thus liberating the carbon dioxide. Large cylinders containing
chemical salts, as previously described, have been mounted on wheels, known as 'chemical tire-en gines,' and are used in many of the larger cities. (See FutE-EsoINE.) For the extinguishing of fire on shipboard a series of pipes have been ar ranged on the upper deck that communieate with the various compartments of the vessel, as the coal-bunkers. the hold. the main (leek. etc. Chem ical agents are placed in the receptacle to which steam may be admitted. and in ease of fire the steam mingles with the million dioxide and the two are conveyed to the place of danger, where they replace the air, smother, and finally ex tinguish the fire. Similar arrangements. some of which are automatic, being made to act when the temperature rises to the danger point, are in use in factories.
Hand grenades. or bombs filled with fire-ex tinguishing solutions of chlorine or ammonium chloride, borax, earbonic-acid gas under great pressure, mixtures of ertleintn chloride. Magne sium sulphate, sodium carbonate. sodium chloride, and sodium silicate, are in common use: but they are of value only in the first stages of a fire. See FIRE-ENGINE.