Sir William Ramsay: The noble chemist

As the International Year of Chemistry starts, one British scientist deserves special recognition.

It was the discovery of a slight discrepancy in the density, or weight, between chemical and atmospheric nitrogen that set the ball rolling.

A lesser scientist might have put the difference down to experimental error, but Sir William Ramsay understood there was a deeper explanation. Another, as yet undiscovered element, must be lurking in the background.

The solution was to devise an experiment designed to strip away all of the known components of air. Whatever was left must be the mysterious unknown element.

What Ramsay found was very strange indeed: a new gas with its very own weight and properties, which did not seem to do anything, or to react with any of the other elements.

He named it argon - the lazy one.

It was the first of five inert gases he would discover, forming the basis of an entire new group of elements known as the noble gases, eventually adding an extra column to the periodic table and winning him the Nobel Prize for Chemistry in 1904.

"Ramsay's incredibly important," says Dr Andrea Sella from University College London (UCL).

"On the one hand he completed the Periodic Table, but he also paved the way for more fundamental explanations - explanations about the deeper connections between the elements that would soon come from quantum mechanics."

One thing that argon does do is light up brilliantly when an electric current is passed through it.

This is an attribute it shares with the other elements Ramsay discovered - neon, helium, krypton and xenon.

Incredibly, the original glass tubes he used to isolate and collect his samples at UCL still exist, and are still glowing red and yellow, purple and green, more than a century later.

Nicknamed "the chief", Sir William Ramsay's achievements - he was dubbed the greatest chemical discoverer of his age - are being celebrated on Wednesday, when a blue memorial plaque commemorating his life and work is unveiled at his home in Notting Hill, London.

The dedication is one of a number of events being organised to mark the International Year of Chemistry, and to raise the profile of the science.

As Professor David Phillips, President of the Royal Society of Chemistry, points out, one pound in every five generated in the UK economy comes from the chemical sciences or chemically based industries.

"If we're serious about addressing the problems we face in the future, problems like climate change, pollution, and resource depletion, then chemistry will be at the heart of those solutions," he says.

And it seems that chemists feel the value of their work is often cast into shadow by those flashier, headline-grabbing disciplines: physics and biology.

"Chemistry has a brand problem," according to Hugh Aldersey-Williams, the author of Periodic Tales.

"It's trapped between physics that's glamorous and mysterious, and biology that's all about us and our bodies.

"Both of those things either fascinate or matter, while chemistry's just the stuff under the kitchen sink."

But the elements are all around us. They produce all the beauty as well as all the nasty smells.

And if you pass an electric current through some of them they'll light up in fantastic red, orange and purple hues.