Fire-Extinguishers.

Hand Grenades.

Prof. F. S. Kedzie of the Michigan State Agricultural College, after a series of analyses and experiments, draws some important conclusions as to the value of hand-grenades, in a paper which he publishes in the Chicago Sanitary News. A Harden hand-grenade was opened, and the solution contained qualitatively analyzed. It consisted of common salt, sulphate of lime, and a small amount of acetate of soda. The principal ingredient was common salt.

The effort was made to determine (1) whether the solution in the grenades had any more extinguishing power than water; (2) if the solution had extinguishing power greater than water, what was the essential ingredient in the solution. The question that first arose regarding the composition of the grenades was: Did they contain carbon dioxide gas or any substance that would give up the gas by being heated? Opening the grenades under water and collecting the gas that escaped it was found that the average amount of carbon dioxide contained was about one cubic inch per grenade. Boiling the solution liberated a slight amount of gas in addition; but altogether the gas was not enough to be of any practical benefit in extinguishing fire. It was then certain that the extinguishing power was in the solution itself. Replacing the solution in the grenade with pure water the extinguishing power, while greater than water thrown from a dish upon flaming boards, was still much less than the power exerted by the solution.

By a careful series of trials it was found that the essential ingredient was common salt. From a number of experiments it was found that when a grenade, or a bottle containing a strong brine, was broken in the midst of the burning kerosene the flames were almost instantly extinguished. A vapor seemed to spread in all directions from where the salt solution struck the board, extinguishing the flame as it went. Strong solutions were also made of sulphate of soda, hyposulphite of soda, borax (biborate of soda), and bicarbonate of soda and tried as fire extinguishers. Some worked as well, but none any better, than common salt in extinguishing fire. The experiment was then made of charging the bottles with brine and generating carbon dioxide by adding lime dust and sulphuric acid and corking tightly. No practical increase in extinguishing power from this addition was noticed. In most instances the carbon dioxide gas escaped from the bottles inside of four days, proving that it is impracticable to attempt to use glass vessels with corks as a means of storing CO₂ under pressure for fire extinguishing.

The conclusion reached from these and many more experiments was that the Harden grenade solution possesses much greater extinguishing power than water alone, and that it owed this power to common salt held in solution. We then constructed some home-made grenades, using flat bottles bound together side by side with wire. Using two bottles in this way insures their being broken in striking the burning body, which would not always occur when only one bottle is used. Bottles thus charged with brine and bound together were broken side by side with the Harden grenades and found to be equally valuable.

It thus appears from the experiment that any person can construct as good and effective grenades as those offered in the market at $7 and $10 per dozen. Bottles filled with brine and placed around the premises will afford considerable protection, especially when used upon the flames when the fire just begins. Salt solutions have the further advantage of not being easily frozen—never enough to burst the bottles.

The Lewis hand fire-extinguisher was next investigated. This consists of a tin tube about two feet long containing thirty-four fluid ounces of soda in weak caustic ammonia. From the trials made we could not notice any appreciable superiority over the salt solution as used in the Harden grenade. It has the disadvantage of not being made to break by being thrown, but must be opened by having a cork extracted from one end of the tube, requiring a smart jerk. The solution is then sprinkled on the fire by the operator.

We herewith append a number of fire-extinguishing compounds, all of which are highly recommended by various authorities:

Munich Fire-Extinguishing Powder.

Common salt43	per cent.
Alum19.5	per cent.
Glauber’s salt5.1	per cent.
Soda3.5	per cent.
Water glass6.6	per cent.
Water22.3	per cent.

Richardson’s Fire-Extinguishing Powder.

Alum4 1/2	pounds.
Common salt10	pounds.
Glauber’s salt1	pound.
Soda1	pound.
Water glass1 1/2	pounds.

Vienna Fire-Extinguishing Powder.

Green vitriol4	parts.
Ammonium sulphate16	parts.
Water100	parts.

Proteau’s Fire-Extinguishing Powder.

Carbonate of soda8	pounds.
Alum4	pounds.
Borax3	pounds.
Carbonate of potash1	pound.
Silicate of soda solution24	pounds.

Mix thoroughly and add 1 1/2 pounds of this mixture to each gallon of water, when required.