Bunsen burners are connected to a source of methane gas to produce a single flame, which is used in many chemical protocols that require heating. The flame intensity is regulated by a valve, at the bottom of the burner. As a source of heat, Bunsen burners play a key role in distillation protocols, as well as in the mixing of solutions and other substances during chemical experiments.
By using heat, scientists can sterilize laboratory equipment that contained biologic samples. Bunsen burners are also used to create a microorganism-free area around them, when left burning during biological experiments that require a totally sterilized atmosphere. Staphilococcus, Escherichia coli and most infection-inducing bacteria found in contaminated material are not heat resistant, and can be eliminated with a Bunsen burner.
Bunsen burners are also used in combustion experiments, as the type of fuel and quantity of available oxygen determines the temperature and color of the flame. In normal conditions, a Bunsen burner produces a yellow flame at about 1,800 degrees Fahrenheit. When scientists add more oxygen to the combustion process, the Bunsen burner produces blue flames.
The preparation of slides for microscopic observation include the fixation of the biologic sample with heat. By using a Bunsen burner, scientists can easily heat-fix slides, thus avoiding washing off the samples during the various staining processes. To heat-fix a bacterial sample, scientists quickly pass the slide five times through the flame, before adding the dyes Crystal Violet and Lugol's Iodine, and rinsing with water.