Classic Projects: Bunsen burner
Image credit: Dreamstime
The Bunsen burner is one of the most instantly recognisable pieces of chemistry lab kit. There can hardly be an engineer today unacquainted with the single flame heat source that has gained worldwide acceptance as the industry standard instrument for heating, combustion and sterilisation in the laboratory.
Its origin dates back to the mid-19th century, when German chemist Robert Bunsen, destined to be one of the great scientists of his generation, took up his teaching post at the University of Heidelberg. As the city had been recently equipped with coal-gas street lighting, Bunsen found that there were gas lines laid to the university. Taking advantage of this distinctly modern fuel supply, Bunsen immediately saw potential for laboratory procedures as well as lighting.
There had been designs for lab burners in the past (including an early version by Michael Faraday), but these were inefficient in fuel consumption, were of unnecessarily complex design and, crucially, failed to deliver a reliable flame of sufficient heat to be of consistent benefit in lab experimentation.
As preparations were under way for the chemistry lab at Heidelberg, the ever-innovative Bunsen set about designing the improved-efficiency burner. With assistance from university mechanic Peter Desaga, he devised the upright desktop unit with the gas inlet at the bottom and the flame at the top. By 1855, Desaga had made 50 of the instruments and they came into use on the opening of the lab.
Two years later, Bunsen published a description of the device, while never patenting it. The chemist, who was renowned for his good-naturedness and altruistic approach to sharing science, decided the design should be open-source, so labs around the world could equip themselves with the new burner without paying royalties to its designer. He preferred that society as a whole could benefit from his invention.
The burner itself was a masterpiece of clear-headed engineering design. Fuelled by methane gas (although liquefied petroleum gases, LPG, such as propane or butane can be used), the intake is at the bottom of the unit, regulated by a needle valve connected to the source tubing by a hose barb. Air intake is via slots on the side of the barrel, using the Venturi effect, and gas is ignited at the top. It is the mixture of methane and air that controls combustion: the more air, the hotter that reaction and the bluer the smokeless, non-luminous flame will appear. When air is cut off, the flame becomes yellow and is termed the ‘safety flame’. The hottest part of the flame is the tip, which burns at 1,500°C (2,700°F). The underlying principle of regulated gas supply to a collared tube is also routinely used in the design and manufacture of camping stoves and lamps.
Bunsen was one of the great scientific visionaries of his day and revered as both a scientist and teacher. He was a pioneer in the fledgling field of spectrometry, the originator of the antidote for arsenic poisoning and still found time to discover the two chemical elements caesium and rubidium. Yet he was outspoken in his desire to see science taught properly, saying a chemist who wasn’t also a physicist “is nothing at all”. Later on in life he claimed that “in my day, we studied science and not, as so often happens now, only one of them”.
The last word on Bunsen is probably best left to Sir Henry Enfield Roscoe, who said: “As an investigator he was great. As a teacher he was greater. As a man and a friend he was the greatest.”
Designer: Robert Bunsen (with Peter Desaga)
Unit cost: Pick one up on Amazon from £28
Bunsen discovered the antidote to arsenic poisoning.
He also invented the zinc-carbon battery.
Bunsen was a pioneer of flash photography.
He won the equivalent of the Nobel Prize in 1860.
Anecdotes of his life were published in the book ‘Bunseniana’.
An earlier burner design was by Michael Faraday.
Bunsen discovered the elements caesium and rubidium.
A ‘Bunsen’ is cricket rhyming slang for a turning pitch (a ‘turner’).
Dr Bunsen Honeydew, The Muppets’ scientist, is named after the German chemist.