Fire is evidence of a combustion reaction between fuel, oxidizer and source of ignition.
The flame is the visible part of the chemical reaction, in a system that maintains itself with the release of light and heat.
Fire was the first energy produced and controlled by man. Through this discovery, it was possible to live in colder regions, the development of cuisine and changes in habits, towards the creation of civilization.
Fire components
The elements that make up the fire are:
- Fuel: substance capable of burning;
- Oxidizing (oxygen): element that intensifies combustion;
- Heat: energy that initiates chemical transformation;
- Chain reaction: sequence of reactions.
Fire is the result of chemical transformation. The fuel, whether solid, liquid or gaseous, is transformed into a gas by the action of heat so that it is then ignited. The most common fuels are: wood, paper, fabric, gasoline, etc.
When the fuel comes in contact with the oxidant, oxygen from the air, and an ignition source, the flame can be generated, that is, the reaction does not occur spontaneously, it is necessary to heat the fuel to a temperature that starts combustion.
Through a chain reaction it is possible that the flame is self-supporting, since the fuel is decomposed into smaller particles that are continuously combining with the oxygen molecules.
The history of fire
It is part of the Paleolithic period, from 4.4 million years to 8000 BC, the domain of fire by man. From the moment that man was able to use discovery to his advantage, fire became a foundation for civilizations.
It is worth remembering that before that, man had already observed fire due to natural phenomena, such as lightning, which cause fires, and eruptions of volcanoes.
The homo erectus was the first human ancestral to control fire, using stones and wood. Through the friction between two stones, the released spark served as a source of ignition to start the flame.
With the emergence of fire, people learned to use it to keep warm, cook food, scare ferocious animals and light environments at night. As a consequence, the manufacture of iron tools was made possible with the development of metallurgy, a technique discovered with the molding of metal on fire.
For the Greeks, there was a myth that fire was stolen from the gods by Prometheus and handed over to men. The Greek philosopher Empédocles used fire to try to explain the composition of matter, along with air, water and earth. For Aristotle, fire could be distinguished from other elements by its properties, hot and dry.