Bunsen, the burner
German chemist Robert Bunsen was born on March 30, 1811 in Gottingen. His father taught fashionable languages on the University of Gottingen and Bunsen too went on to earn his doctorate there. Before he returned to this place as a lecturer, he travelled throughout Europe for 3 years. He additionally taught on the Universities of Marburg and Breslau, nevertheless it was as a professor at Heidelberg, the place he taught from 1852 till his dying in 1899, that he’s finest related to. Bunsen by no means married, as an alternative selecting to dwell for his college students and his laboratory, establishing an wonderful lab and remaining in style together with his pupils all through.
Robert Bunsen
| Photo Credit:
Heidelberg University Library / Wikimedia Commons
Bunsen was first drawn in the direction of natural chemistry and he was in a position to produce what stays one of the best antidotes for arsenic poisoning – iron oxide hydrate. Bunsen, nonetheless, misplaced one of his eyes when working with cacodyl cyanide, an arsenic compound, forcing him to maneuver to different disciplines.
In case you’re feeling conversant in the title Bunsen, that’s since you might need encountered the Bunsen burner in your chemistry labs. Along together with his laboratory assistant Peter Desaga, he constructed the gadget that now bears his title in 1855. Part of chemistry labs the world over, Bunsen burners enabled its inventor to review emission spectra from heated components. He put it to nice impact and showcased the ability of spectroscopy as a device for scientific analysis.
Kirchhoff’s key contributions
Born on March 12, 1824 – practically 13 years after Bunsen – in Konigsberg, Prussia (now Kaliningrad, Russia), Gustav Robert Kirchhoff is a German chemist, mathematician, and physicist. He married the daughter of his arithmetic professor and the couple moved to Berlin quickly after their wedding ceremony.
Gustav Robert Kirchhoff.
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Smithsonian libraries / Wikimedia Commons
It was on the University of Breslau, the place he’d change into a professor on the younger age of 26, that Kirchhoff first encountered Bunsen. The duo would go on to do nice issues collectively, however Kirchhoff has loads of claims to fame on his personal.
Both Kirchhoff’s legal guidelines of electrical circuits and Kirchhoff’s legal guidelines of thermodynamics are, unsurprisingly, named after him in his honour. He made basic contributions in serving to perceive the emission of black-body radiation by heated objects, electrical circuits, and spectroscopy. The time period “black body,” in truth, was coined by Kirchhoff in 1860, the identical 12 months he found caesium with Bunsen. He additionally used emission spectra to review the sky and recognized 30 components in the solar.
Bunsen-Kirchhoff partnership
In 1854, Bunsen satisfied Kirchhoff to maneuver to Heidelberg in order to facilitate their collaboration additional. They have been engaged on analysis to try to show that every one pure components have a distinct spectrum that they emit. While work in this area was already on for practically a century, if no more, such research lacked the systemic strategy and cautious examination that this duo wished to carry to the desk.
Partnering for this work in 1859, Bunsen advised utilizing filters to dam colors just like the yellow of sodium compounds. He believed that such an association would facilitate the detection of much less intense colors which are additionally emitted by different components.
Kirchhoff, in the meantime, wished to adapt a methodology that a couple of others – English mathematician and astronomer John Frederick William Herschel, and English scientist, inventor, and pictures pioneer William Henry Fox Talbot – had employed a few many years earlier. He wished to enhance Bunsen’s approach by adapting the Herschel/Talbot methodology whereby gentle was handed by means of a prism. Bunsen and Kirchhoff successfully got here up with their model of the spectroscope.
Kirchhoff (left) standing alongside Bunsen.
| Photo Credit:
University of Pennsylvania Library / Wikimedia Commons
In 1860, the duo analysed the spectral traces of spring water from Durkheim. Known to be wealthy in lithium compounds, Bunsen observed one thing completely different in the spectra. Apart from the anticipated spectral traces from sodium, lithium, and potassium, Bunsen additionally recognized a new sky-blue doublet that he hadn’t seen earlier than. He named the brand new aspect caesium, naming it after the Latin phrase for “sky blue.” The duo made their discovery public by asserting it on May 10, 1860.
Having managed to get simply 2 mg of caesium chloride from 10 litres of spa water, Bunsen commissioned a close by chemical manufacturing unit to evaporate 12,000 gallons of spring water in order to isolate caesium and research its properties. Even although he did not get hold of pure caesium, he was in a position to set up the relative atomic mass of the aspect as 128.4 (we all know that 132.9 is the worth now).
Bunsen and Krichhoff went on to look at the presence of one other alkali steel in spa water by observing darkish pink in the spectral traces. They named this aspect rubidium, once more from the Latin for “dark red.” While the duo have been profitable in isolating rubidium, they couldn’t replicate the success in the case of caesium.
Setterberg isolates caesium
The credit score for first isolating caesium goes to Swedish chemist Carl Theodor Setterberg. Born in 1853 in Skaraborg, Sweden, Setterberg set about residing a lifetime as an industrial chemist. When doing analysis for his PhD, August Kekule – his supervisor and professor of chemistry on the University of Bonn – tasked him with isolating caesium.
Following the extraction of lithium from lepidolite, an ore of the mica group, there’s a lot of waste materials that is still. Setterberg determined to make use of this as his start line for isolating caesium. The waste ore was transformed into a combination of potash alum, together with these of rubidium and caesium. With the assistance of fractional crystallisation, Setterberg was positive he may separate the alum salts.
This is precisely what occurred as Setterberg began off with round 350 kg of the waste ore, earlier than ending with 10 kg of a caesium compound. This was greater than Bunsen ever had, permitting Setterberg to strive completely different methods to isolate caesium.
After a failed experiment when he tried the carbon discount methodology that Bunsen had efficiently used to acquire rubidium, Setterberg switched to electrolysis. Setterberg discovered that cyanide-based mixtures of caesium salts have been best for his goal as he efficiently remoted the aspect in 1882. He went on to explain some of its properties in the identical 12 months, giving its melting level and density. Setterberg’s contribution, nonetheless, is usually missed out when speaking in regards to the discovery of caesium.
The world of science can really feel unusual to many onlookers to the extent of seeming incongruous on events. The discovery of caesium is a case in level. Wherein Setterberg’s isolation is usually relegated to a footnote in the invention story, the other rings true in the case of fluorine. Even although Swedish chemist Carl Wilhelm Scheele made vital contributions to the understanding of fluorine in the 18th Century, it’s French chemist Henri Moissan, who first remoted the aspect over 100 years later in 1886, who’s all the time instantly related to it.
Caesium information
A chemical aspect with image Cs and atomic quantity 55.
It is very reactive and is a tender, silvery-gold alkali steel.
A liquid simply above room temperature, caesium has a melting level of 28.4 °C.
The present definition of a second relies on caesium.
The most well-known use of caesium is in the atomic clock.
Published – May 10, 2025 12:20 am IST
