One Thousand Ways to Make Money by Page Fox

658. FIRE EXTINGUISHER.--Now we will give you the secret of a fire

extinguisher that will do more with the same amount of chemicals used than any patented fire extinguisher in the world. A small demijohn is filled with a substance that looks like water, but sells for the price of brandy. Half a dozen of these demijohns scattered about a building will protect it from conflagration, for it contains a liquid which is the most inimical to fire that is known. A gallon of it thrown on the flames will subdue any ordinary fire, and yet--here is the secret--it is nothing but aqua-ammonia. _Section 19. Money in the Laboratory._