158 PREVENTION AND EXTINGUISHMENT OF FIRES. 



The action of water upon fires is rather mechanical than chemical,, 

 quenching it by "physical contact with the burning body, covering it and 

 excluding the oxygen of the air." Also, "it instantly reduces the tempera- 

 ture of ignited substances by vaporization. Bj a sudden change from a 

 liquid to a vapor, it robs the substance of the heat necessary to keep the 

 up the combustion and thus extinguishes it." 



While owing to its extreme abundance and cheapness in most localities- 

 and at most times, water is the most useful and serviceable agent in the ex- 

 tinguishment of fires, yet from the damage done by it, the difficulty of ap- 

 plying it under all circumstances and the immense amount required to sub- 

 due an ordinary fire, it will not be surprising if, before another century 

 elapses, it will have been superseded by other agents more effective and less 

 objectionable. 



Numerous means have been proposed for rendering its use more effective 

 and its application more immediate and direct than at present, when we de- 

 pend almost wholly upon our fire departments, and are obliged to await 

 the arrival of the steam fire engine with its terrific floods of water, which ^ 

 however well directed, seem in many instances to do more damage than 

 would have resulted from the fire if left to itself. Much good will be ac- 

 complished by the discovery of some means of applying this agent strictly 

 as an extinguisher, in quantities regulated to the amount of fire, in place of 

 the present plan of applying it in volumes ten if not one hundred times 

 more copious than is requisite, i. e, mathematically requisite, for the mere 

 extinguishment of the flames. 



One plan proposed for regulating the quantity and force of the water ap- 

 plied to flres is that of stand pipes in factories and warehouses, filled from 

 the water-works or from tanks overhead and running from basement to 

 roof, with appliances of hose and nozzle on each floor, and upon the roof, 

 so that they can be brought to bear instantly at the points where they are 

 required. 



Perforated pipes placed along the ceilings of rooms, above the stages of 

 theaters and over those localities in workshops and stores where inflam- 

 mable materials are exposed and handled, may be found of the greatest use, 

 having the advantage over engines of being always at hand and ready for 

 use, and of applying the water in quantities appropriate to the occasion, 

 just where needed and without unnecssary or injurious violence. 



Nelson Carl proposes to carry pipes upon the roofs of buildings, to per- 

 form the double purpose of wetting them in case of flre, and thus prevent- 

 ing their ignition, and also of acting as conductors of lightning. Particu- 

 larly would such contrivances as those described above be found extremely 

 efiicacious in very tall buildings, where the water thrown by the engines 

 only falls upon them in 8j)ray and is converted into steam or driven away 

 by the heated currents of air. 



II. It is very apparent that if we can mix with the water used for ex- 

 tinguishing conflagrations some gas which is itself an extinguisher of flames, 



