An Element of Interest...

Discovered spectroscopically in the sun by Sir Joseph Lockyer of England in 1868. Independent spectroscopic discovery in the sun by Pierre Janssen of France in 1868. Isolated on earth by Sir William Ramsay of England in 1895.

Helium is tasteless, odorless, colorless, normally nontoxic, and the second most abundant element in existence. It launches rockets, cools nuclear reactors, lifts weather balloons, and treats asthmatics.

An old trick is to breathe from a helium-filled balloon. When you talk with that breath, your voice is very high-pitched, like Donald Duck's. Helium is not very dense, so it's easier for the larynx to vibrate surrounded by helium than by air.

The People's Almanac #2 by David Wallechinsky and Irving Wallace, William Morrow and Company, Inc., New York

Not many people know this, but 1995 is the 100th anniversary of the discovery of helium, the lighter-than-air gas that fills Mickey Mouse balloons and makes your voice sound like Donald Duck. Having a 100th birthday may not seem particularly remarkable--until you realize that helium is the second most common element in creation, accounting for one in every ten atoms in the Universe--which prompts the obvious question: how in the world did we manage to miss it until 1885?

The simple answer is that helium is both chemically inert and extremely light. Its inertness ensures that it rarely gets trapped in compounds, while its lightness means that as soon as it is released into the air it floats off into space.

And space is where the gas was first found. Helium is unique in being the only element to be discovered on the Sun before it was discovered on Earth. The man who spotted it there was Norman Lockyer, a civil servant from Wimbledon who, among other things, wrote the first book on the St. Andrew's rules of golf, founded London's Science Museum in South Kensington and launched the international science journal Nature, which he edited for 50 years.

On 20 October 1869, Lockyer pointed his 6-inch telescope at the sun and examined the light with a spectroscope. In the spectrum of a solar prominence he was surprised to see a curious yellow line. The line was observed the same year from India by the French astronomer Pierre Jules Cesar Janssen. Both men failed to reproduce the spectral feature in the laboratory and, in 1870, Lockyer make the bold suggestion that the line was the "fingerprint" of an unknown element. Lockyer was ridiculed for proposing the existence of "helium" and had to wait many years to see his critics silenced. The man who proved him right and found helium on earth was the Scottish chemist William Ramsay, the only person to discover an entire group of the periodic table of elements--the noble gases. It is the centenary of Ramsay's discovery, not Lockyer's that we are celebrating this year.

In March 1895, while examining the spectrum of gases given off by a uranium mineral called cleveite, Ramsay spotted a mysterious yellow line. Lacking a good spectroscope, he sent gas samples to both Lockyer and to William Crookes, a physicist famous for experimenting on cathode rays and being an advocate of telepathy. Within a week Crookes had confirmed that the gas was the same as the one Lockyer had observed. Lockyer was beside himself with joy as he squinted through the spectroscope at the "glorious yellow effulgence" he had first seen on the Sun a quarter of a century before.

Today, helium is used in arc-welding equipment, lasers and gas-cooled nuclear reactors. Deep-sea divers avoid the bends by breathing a mixture of helium and oxygen. But helium's greatest claim to fame is as the ultimate refrigerant. Boiling at the lowest temperature of any substance--a mere 4.2 K or -269 ^oC--liquid helium is used to cool anything from astronomical detectors to superconducting magnets. In fact, in its liquid state, helium can lay claim to being one of the most bizarre substances known. when cooled below 2.18 K it becomes a superfluid, able to flow without friction, squeeze through impossibly small holes and even run up hills. Helium is also the only substance that never solidifies. Hell will freeze over long before liquid helium does.

But there is a final twist to the peculiar story of this peculiar substance. although most of the helium in the Universe was forged in the first few minutes of the big bang, with a small amount cooked later in stars, most of the helium on earth comes from the radioactive decay of heavy nuclei deep in the planet. some finds its way into deposits of natural gas.

For most of this century the world's precious supply of helium has escaped from natural gas wells into the air. Only in 1958 did politicians heed the warnings of influential scientists including John Bardeen, the inventor of the transistor, that all our helium would be gone by 1980. Congress reacted by spending $1 billion--an astonishing sum in the 1950s--on a separation plant in Amarillo, Texas, and began stockpiling helium in empty gas wells.

As it happened, helium turned out to be crucial to the success of NASA's space--programme. The most powerful rocket motors are fueled by hydrogen and oxygen, both of which have to be carried in liquid form, and helium is the ideal refrigerant. In fact, it was helium carried to the Moon on the Apollo spacecraft that determined how long the astronauts could stay on the lunar surface. Once the helium had boiled off it would have been impossible to keep hydrogen and oxygen in liquid form and the spacecraft would have been stranded.

Thanks to the conservation measures, helium supplies were not exhausted by 1980. and other rich sources of the gas were discovered. however, sources of helium have remained few and far between because the geology of natural gas wells must be very special in order to hold onto it in commercial quantities.

Against this background, the worldwide consumption of helium has increased by between 5 and 10 percent a year in the past decade, which the biggest growth in its use as a coolant for the superconducting magnets in magnetic resonance imaging (MRI) body scanners. Present helium consumption is estimated to be about 100 million cubic metres, and is predicted to continue rising by 4 to 5 percent a year.

No one is claiming that we are in imminent danger of running out of helium--there should be at least 20 years supply left. However, new sources of the gas will have to be found to meet the ever-growing demand. If not, God forbid, we may have to celebrate helium's 200th birthday in the year 2095--without any Mickey Mouse balloons.