THE WONDER OF GASES
STEVE WEINMAN, EDITOR

SCIENCE WAS NOT MY STRONG POINT AT SCHOOL. In fact I believe I was written off prematurely by my chemistry and physics teachers, who really should have made more effort.
Later in life, I coped with diving science at the level of Boyle's Law and partial pressures (10-year-olds seem to manage it easily enough, after all) but let's say I don't spend much spare time reading New Scientist.
So my apologies if this is old news to you, but I was mildly shocked to learn over the dinner-table that the Earth is fast running out of helium, the staple diet of mixed-gas divers.
Though familiar with the idea of endangered species, I had never considered that there was such a thing as an endangered gas. In fact I thought it was a wind-up until I did some checking.
It seems that nearly all the world's helium comes from the area around Amarillo, Texas, a by-product of natural gas that escapes if not bottled during the refining process.
It doesn't just escape into the atmosphere, however. Helium is so light that it can skip clear of gravity and dissipate into the vastness of the universe. Discovered not that long ago, this inert gas has survived on Earth as long as it has only because the Americans have stockpiled it.
Yet it seems that within decades all the world's natural helium will be lost in space. Bad news for balloon-sellers, entertainers who want to speak like Joe Pasquale and those who rely on the gas as a super-coolant for everything from MRI scanners to rocket-fuel tanks.
I asked some technical divers about this, but few seemed bothered by the prospect of a helium-free world. They reckon it will see out their own deep-diving days, and that future generations will find their own more sophisticated solutions.
Lakeside Diving's Kevin Side, a popular supplier of helium, reckoned mixed-gas divers were switching to rebreathers at such a rate that their overall helium requirement was reducing drastically anyway.
Of course, we may well have run out of oil by the time the last of the helium drifts away, so getting to the dive site could be an even more fundamental concern.
And it seems there are massive supplies of helium on the Moon, so it's just a matter of mining it and transporting it to terrestrial dive shops. For now helium prices remain steady, so no need to panic-buy.
I was just absorbing all this fascinating, if surreal, stuff when I heard the latest theory on diving gases - that nitrox may be an aphrodisiac.
The evidence so far seems to be mainly anecdotal (News, page 20). But having in the past considered the effects of gases on the body mainly in terms of tissue-loading and expansion, this seems to add an exciting new dimension. Are some mixes more potent than others? Will we be subjected to a torrent of email spam offering performance-enhancing nitrox at special rates?
There is clearly far more to diving gases than I had ever imagined.