Soda-Acid Fire Extinguisher

Start with the reaction on its own, in the open, before it drives anything.

1. Put a measured spoon of sodium bicarbonate in a beaker.
2. Add vinegar and watch the fizz.
3. Repeat over a balance and record the mass lost.

NaHCO₃ + acid → CO₂↑ + water + salt

Prove the gas puts fire out before building anything that sprays.

1. Stand a short candle in a tall jar and light it.
2. Generate CO₂ in a separate beaker and carefully pour the invisible gas — not the liquid — down into the jar.
3. The flame goes out.

The mechanism is the point: two reagents kept apart until the moment of use.

1. Half fill a strong bottle with bicarbonate solution.
2. Suspend a small open vial of vinegar inside the neck so it stays upright and does not spill.
3. Fit a stopper with a narrow outlet tube reaching below the liquid surface.

Point it away from people. Do this outside.

1. Invert the bottle sharply.
2. The vial empties, gas is generated, pressure rises and liquid is driven up the tube and out.
3. Measure how far the jet reaches and how long it lasts.

The chemistry was known long before the device. French inventor François Carlier patented a soda-acid extinguisher in the 1860s, and Almon M. Granger patented an American version in 1881; the basic arrangement was widely copied and there is no single clean line of invention. Soda-acid units — usually a tall copper or brass cylinder on a wall bracket — were the standard building extinguisher across Europe and North America for roughly seventy years.

Why they were retired, which is the interesting part. Three reasons, all learned from accidents. They discharge a water-based salt solution that conducts electricity, so using one on an energised electrical fire could electrocute the operator — and electrical fires became far more common through the twentieth century. They are useless on burning oil or fat, where water sinks under the fuel, flashes to steam and throws burning liquid outward. And some designs had to be inverted to fire, which meant they could not be shut off once started and had to be fully discharged and recharged.

What replaced them: extinguishers classified by what they are for. Water for ordinary combustibles, foam and wet chemical for cooking oils, CO₂ and dry powder for electrical and flammable liquids. The coloured band on a modern extinguisher is the direct descendant of the discovery that one extinguisher for all fires is a dangerous idea.

What this build is: a demonstration of the pressure-generation principle, not a fire-fighting device. It has no gauge, no certified vessel, no shut-off and no rated capacity. Never rely on it, and keep a real extinguisher to hand whenever you light the candle in step 2.