Arthur C. Clarke once famously pronounced that any sufficiently
advanced technology is indistinguishable from magic. The reverse,
of course, is not so true. Just because something seems to need
magic to explain it does not make it an advanced technology: a more
conventional explanation, such as sleight of hand, is usually involved.
Even so, some apparently magical ideas survive even when there
is no decent scientific explanation for them. One is that applying
a magnetic field to a water pipe can soften the water flowing through
it and so prevent the pipe from scaling up. Devices based on this
idea crop up regularly in the classified advertisements, alongside
improved potato-peelers and better mousetraps. Domestic versions
cost around $300; industrial ones up to $30,000. Physicists, unable
to explain how such machines could work, have dismissed them for
years. Physicists, it appears, are wrong.
The evidence comes from Simon Parsons and his team at Cranfield
University in Britain. They put the tale to the test and found that
it is not as tall as it seems. Indeed, given the right combination
of magnetism, temperature, acidity and water flow, they found that
the rate of scaling could be halved. This is potentially impressive.
Dr. Parsons reckons that scaling costs British industry $1.5 billion
a year. Halving that cost would be a useful gain. What is not clear
is just how the process works. On March 14th a seminar at Cranfield,
which will be addressed by physicists from America and Japan, as
well as Europe, will explore the problem.
One clue they will have to go on is that the limited amounts of
scale produced in Dr. Parson's experiments do not form a solid crust
that requires major surgery to remove, but rather a powdery layer
that can be eliminated with a stiff brushing. Examined under an
electron microscope, the crystals that make up this layer look circular.
Those in common or garden limescale are rectangular. It seems that
the magnetic field changes the way in which the calcium carbonate
that makes up scale crystallizes.
Dr. Parson sees four possible explanations. The most esoteric is
that the magnetic field is changing the shape of the orbitals occupied
by the electrons surrounding the atoms involved. This would certainly
change their chemical reactivity. But he thinks it is extremely
unlikely that his magnets could have this effect.
Another possibility is that the field is causing impurities in
the water, such as iron atoms, to stick together in ways that form
nucleation sites: places around which calcium carbonate can easily
crystallize. By forming in the flowing water, rather than accumulating
on the edge of the pipe, the crystals would not fur things up.
The third idea is that the magnetism changes the way that calcium
ions attract water molecules. When ions (electrically charged atoms)
dissolve in water, their charges cause nearby water molecules to
cluster around them. This, of course, interferes with their ability
to react with other ions. If you make changes in the nature of its
protective shell, you change an ion's reactivity.
The fourth theory is that the field distorts the electrical charge
that is carried by small particles of calcium carbonate that have
already formed in the water. This, in turn, affects the way they
stick together to form large particles.
For Dr. Parson's money, the fourth explanation is the most likely.
It is the only one that fits with the observation that the magnets
work only on flowing water. Whereas electrically charged objects
sitting still in a magnetic field do nothing, those moving through
a field generate a further electrical charge, which will also change
their attractiveness to each other.
Dr. Parson's money, though, is not the only interested cash. The
oil industry, in particular, is watching the work done at Cranfield.
Oil wells face major scaling problems from the highly mineralized
waters extracted along with the pay dirt. Chemical treatment costs
as much as $750,000 a year for a typical North Sea platform, and
some magnetic devices are already being tested; an industry that
is often based on hunches is certainly willing to give them a try.
But without a theoretical explanation for the magic boxes, which
would give some idea of their limitations, hard-headed engineers
are reluctant to invest in them more widely. Perhaps, if Dr. Parsons
and his collaborators can manage to explain this particular magic,
a new technology will be born.
(Note: Dollar amounts have been changed from British Pounds to