At the end of 19, people began to use sulfate carbonate fire extinguishers. 1905, Professor Laurent of Russia invented a foam fire extinguishing agent in St. Petersburg. Its principle is to mix aluminum sulfate with sodium bicarbonate solution and add stabilizer, and then spray it to produce foam containing carbon dioxide, which floats on burning oil, paint or gasoline. This kind of foam can effectively isolate oxygen and extinguish the flame.
1909, American Davidson obtained a patent to use a carbon dioxide fire extinguisher to extrude carbon tetrachloride, which will turn into a heavier nonflammable gas to extinguish the flame. Since then, humans have invented small fire extinguishers such as dry powder fire extinguishers and liquid carbon dioxide fire extinguishers.