The most effective method of extinguishing fire is by means of a solution used in chemical fire apparatus. This solution is much more efficient for fire-extinguishing purposes than plain water, because the chemical solution does everything that water can do exactly in the same way and for exactly the same reasons. In addition, it forms a considerable blanket of fire-extinguishing gases which are heavier than air and better supporters of combustion, and in this manner shuts off much more effectively the access of air (oxygen) to the fire.

Chemical fire-extinguishing solution extinguishes fire more by smothering than by cooling. The only drawback is that the supply of chemical solution must necessarily be comparatively limited. However, a reasonable supply of chemical solution, instantly available, makes a large supply of water unnecessary.