Foam Fire Extinguisher.
Consul Thomas H. Norton, of Chemnitz, submits the following description of a new German mechanism for fighting fire:
Fire chiefs and insurance companies are familiar with the dangers and difficulty inherent to combating conflagrations where petroleum, gasoline, benzine, or other liquid hydrocarbons, lighter than water, are involved. As is well known, the attempt to extinguish with streams of water in such cases results usually in a spreading of the inflammable liquid, an increase of the area of combustion and a greater intensity of conflagration. The use of steam or of a current of inert gas is available only for incipient conflagrations in well-closed rooms. It presupposes, also, the permanent location on the spot of stationary apparatus for the purpose. A distinct step forward in the means of battling with such conditions has been made in Germany, where the use of a tenacious foam, dissipated with difficulty, has been found of great value in cutting off the supply of air necessary to maintain combustion and thus extinguishing flame. The method and the requisite apparatus have been perfected by a wellknown Prussian manufacturing company at Salzkotton, near Minden, Prussia, and have been submitted to exhaustive tests by fire chiefs and others interested in the question of protection against the dangers from combustible liquids. The apparatus employed consists of a simple metal cylinder provided with a long spout and divided into two chambers. One chamber is charged with an aqueous solution of potash alum and sodium sulphate, the other with a similar solution of sodium bicarbonate, sodium sulphate and licorice-root extract. The cylinder is so arranged that, on being inclined or reversed, the two solutions mingle as they issue from the spout. There is no pressure evolved, and, consequently, the liquid does not issue with sufficient force to cause a spattering of the burning hydrocarbon upon which it may be poured. The result of the chemical reaction between iwceu me the aium alum auu and me the bi01 lotion lution carbonate of of carbon carbon is a prompt dioxide, rliovi,!., evowhich in contract with the licorice solution, forms an exceedingly stiff and persistent foam. Such a layer of foam containing an inert gas upon the surface of a burningliquid effectually cuts off all access of air andcombus tion necessarily ceases. The temperature of the liquid may have reached a sufficiently high point, so that, through evaporation, bubbles of the vaporised hydrocarbon rise for a time through the stratum of foam,and tongues of flame flutter over its surface. These soon cease, for, simultaneously with the evolution of the carbon dioxide, there is a loss of latent heat, the temperature of the foam-yielding soluAT LOUISVILLE. tion falls, and this, in turn, cools down the com bustible liquid. The solution acts thus in a double manner as a protective agent. Among the numerous tests to which the apparatus has been submitted by the heads of fire departments, the following, by the chief of the Hanover department, might be cited:
An iron vessel, by 5½ ft. in size and 4 in. deep, received a charge of 18 gal. of benzine. Benzine was likewise poured on the ground where the vessel rested. The liquid in the vessel and outside the same was lighted and allowed to burn for three minutes. The contents of the two foam-extinguishers were then allowed to flow over the whole. Combustion was promptly arrested. The superincumbent layer of foam was then removed and the benzine lighted anew. The attempt was now made to extinguish the flames by means of water, first, with a simple, portable house-extinguisher, and then with the use of the city water supply issuing from a 2-in. hose. In neither case could the fire be extinguished. On the contrary, the area of combustion was rapidly extended, until it covered over 40 sq. yds. It was then necessary to discontinue the use of the hose, on account of the danger to the buildings surrounding the court in which the experiment was conducted. The success attendant upon this and similar tests has led to the conviction among authorities on protection against fire that the foam-extinguisher is capable of rendering valuable service in all places where combustible liquids are stored, such as groceries, drug stores, etc., and especially in automobile garages and motor-yachts. ‘ The use of liquid fuel for rapid locomotion by land, water and air is extending so swiftly that the new protective will meet a distinct need in every land. It would be an indispensable adjunct to the introduction of explosion motors in ocean liners.