Celebrating 22 Years on the Web
Find science on or your birthday


Stories About Chemistry


83. A Chemical Prism

By a strange coincidence, this scientist’s name and profession are consonant with his discovery.

He was a botanist and his name Mikhail Tsvet. Tsvet is the Russian for colour. The botanist Tsvet was interested in chlorophyll which, as we know already, is the colouring matter of green leaves.

But Professor Tsvet also knew many chemical procedures. In particular, he knew that there were substances (adsorbents) which could retain (adsorb) many gases and liquids on their surfaces.

He ground a leaf into a green paste and treated it with alcohol. The paste lost its colour, which meant that all its colouring matter had been extracted by the alcohol.

Then he filled a glass tube with chalk moistened slightly with benzene; into this tube he poured the solution containing the chlorophyll.

The upper layer of the chalk powder turned green.

The scientist washed the chalk in the tube with benzene, adding it drop by drop. The green ring budged and then began to move downwards And then—oh wonder!—it separated into several bands of different colours. There were a yellow-green, a green-blue and three yellow bands of different shades. It was a curious sight that the botanist Tsvet observed. And this sight proved a most important find for chemists.

It indicated that chlorophyll was a complex mixture of several compounds, different, though close, in molecular structure and properties. What is now called chlorophyll was only one of them, true, the most important one. All these substances had now been separated from one another by a very simple method.

All of them had been adsorbed by the chalk, but each in its own way. The strength of retention of each compound by the surface of the chalk powder was different. And when the benzene (the eluant) passed through the tube, it carried off the substances in a definite sequence. First those that were held less strongly, and then those that were retained more strongly. This caused the separation.

Like a prism resolves solar light into the spectrum colours, so did the column of adsorbent (the “chemical prism”) split up the complex mixture of substances into its component parts. This new method of analysis discovered by Tsvet in 1903 was christened chromatography by its author. This word comes from the Greek for “colour writing.”

Today the method of chemical “colour writing” is one of the most important instruments in all analytical laboratories the world over.

But the fates of many scientific discoveries are inscrutable. Some are forgotten, sometimes for many years, only to shine afterwards on the scientific horizon like stars of the first magnitude. So was it with chromatography. It was actually remembered only in the forties, and nobody ever regretted this.

< back     next >

- 100 -
Sophie Germain
Gertrude Elion
Ernest Rutherford
James Chadwick
Marcel Proust
William Harvey
Johann Goethe
John Keynes
Carl Gauss
Paul Feyerabend
- 90 -
Antoine Lavoisier
Lise Meitner
Charles Babbage
Ibn Khaldun
Ralph Emerson
Robert Bunsen
Frederick Banting
Andre Ampere
Winston Churchill
- 80 -
John Locke
Bronislaw Malinowski
Thomas Huxley
Alessandro Volta
Erwin Schrodinger
Wilhelm Roentgen
Louis Pasteur
Bertrand Russell
Jean Lamarck
- 70 -
Samuel Morse
John Wheeler
Nicolaus Copernicus
Robert Fulton
Pierre Laplace
Humphry Davy
Thomas Edison
Lord Kelvin
Theodore Roosevelt
Carolus Linnaeus
- 60 -
Francis Galton
Linus Pauling
Immanuel Kant
Martin Fischer
Robert Boyle
Karl Popper
Paul Dirac
James Watson
William Shakespeare
- 50 -
Stephen Hawking
Niels Bohr
Nikola Tesla
Rachel Carson
Max Planck
Henry Adams
Richard Dawkins
Werner Heisenberg
Alfred Wegener
John Dalton
- 40 -
Pierre Fermat
Edward Wilson
Johannes Kepler
Gustave Eiffel
Giordano Bruno
JJ Thomson
Thomas Kuhn
Leonardo DaVinci
David Hume
- 30 -
Andreas Vesalius
Rudolf Virchow
Richard Feynman
James Hutton
Alexander Fleming
Emile Durkheim
Benjamin Franklin
Robert Oppenheimer
Robert Hooke
Charles Kettering
- 20 -
Carl Sagan
James Maxwell
Marie Curie
Rene Descartes
Francis Crick
Michael Faraday
Srinivasa Ramanujan
Francis Bacon
Galileo Galilei
- 10 -
John Watson
Rosalind Franklin
Michio Kaku
Isaac Asimov
Charles Darwin
Sigmund Freud
Albert Einstein
Florence Nightingale
Isaac Newton

by Ian Ellis
who invites your feedback
Thank you for sharing.
Today in Science History
Sign up for Newsletter
with quiz, quotes and more.