(1) 8 lb. carbonate of soda, 4 lb. alum, 3 lb. borax, 1 lb. carbonate of potash, and 24 lb. silicate of soda solution are mixed together; l 1/2 lb. of this mixture is added to each gal. of water when required for use. The object is to cover everything with a fireproof film or deposit.
(2) A committee of the Polytechnic Society of Munich has lately issued a report on the means to be adopted for extinguishing burning petroleum. This states that since concentrated water of ammonia evolves a great amount of gas when heated, and this gas is unable to sustain the combustion of any substance, it may be asserted that petroleum will not continue to burn even in a room filled with atmospheric air wherein a considerable proportion of ammonia gas is present. The place where the petroleum is stored must be broken up in compartments, so as to limit the bulk. The ammonia water must contain at least 10 per cent, of the gas. The proposed method of employing the agent is to keep a bottle full of it on each cask; the bottle and its contents would remain intact till fire caused the destruction of the one and the liberation of the other, so that there would be no loss except when needed.
(3) The now well-known extincteur introduced by Sinclair is a vessel filled with water charged with carbonic acid gas under great pressure.
(4) Foster, of Bolton, has introduced an extinoteur in the form of a portable pump, which can draw a continuous water supply from any source, and saturate it with carbonic acid under pressure before emitting it in a jet.
(5) The carbonic acid is produced by decomposing a carbonate by an acid. If sulphuric acid be poured on a solution of soda carbonate, violent effervescence takes place, because the latter consists of carbonic acid gas combined with sodium oxide; the stronger acid (sulphuric) displaces the weaker, and itself combines with the sodium oxide to form soda sulphate, setting free the carbonic acid in a gaseous form. If this occurs in a close vessel, the carbonic acid accumulates with increasing pressure. In extincteurs, different means are adopted for liberating the sulphuric acid when action is to take place. In Sinclair's, a strong metallic vessel is nearly filled with soda carbonate solution, the acid being kept in a stoppered bottle in the midst of the solution. For use, the bottle is broken, with consequent liberation of the acid and generation of the gas, which is let out by a tap and tube. Jn Merry weather's, the acid is kept in a bottle with a loose-fitting stopper, and for use, the whole apparatus is momentarily inverted, thus pouring the acid into the solution; in this way, fragments of glass from the bottle are avoided.
In Shand and Mason's, the acid bottle is broken by a weight falling upon it, and provision is made for straining back broken glass from the outlet pipe.
(6) Dumas has discovered that water saturated with alum has superior value in extinguishing fires - a value supposed to be due to the coating it gives to objects wet with it, which prevents contact with the oxygen of the air, and thus diminishes the rapidity of the combustion. Experiments are to be made by supplying the firemen of Paris with instruments to throw It.