Faraday鈥檚 early duties as Davy鈥檚 temporary valet-cum-assistant could safely be omitted from a bald account of their scientific endeavours. But to discover how and why such figures emerged as great chemists we need to know something more than end results. It is, after all, not so trivial to find out that Dorothy Hodgkin鈥檚 botanist mother gave her a copy of Bragg鈥檚 Concerning the Nature of Things when she was 15; or to be reminded just how antisocial, anti-establishment and downright cantankerous was Joseph Priestley; or how the rise of the professional chemist in the 19th century took place under the dual influences of the Industrial Revolution and Romanticism.

Creations of Fire does not contain any startling new insights. But it should win over anyone who switches off at the sight of a list of worthy achievements. Here they are interspersed with a generous sprinkling of human failures and foibles. Cathy Cobb and Harold Goldwhite succeed in sketching 鈥渁 humanised history of chemistry鈥�; an overview of the science from prehistoric metallurgy to superheayy elements that also highlights the personalities involved and throws in potted history for wider context. Their account is generally extremely readable.

The book is badly let down by its presentation, however. There are few illustrations. Worse, instead of stressing the links between people and events, the book divides these elements with subheadings of excruciating dullness. All this is rather a pity. It leaves the overall impression of an unreacted mixture of interesting ingredients, rather than the elegant synthesis great chemists so often sought.

The shape of glass and the foam head on beer are known to influence flavour, but exactly how remains something of a mystery. Guy Derdelinckx, Freddy Delvaux and colleagues used a combination of sensory analysis and 15 trained tasters to investigate how four common shapes of beer glass 鈥� thistle, chalice, cylindrical and cup-shaped 鈥� affect the flavour of a representative sample of Belgium鈥檚 400-odd beers.

Each Belgian beer is associated with a particular type of glass and is served with a head. The researchers鈥� results suggest that brewers who select a glass shape only on grounds of cost, weight and image 鈥� primarily its ability to maintain a large head 鈥� may not always be making the most of their beer鈥檚 flavour.

Flavour is largely a matter of smell, and the foam acts as a barrier to some of the volatile flavour molecules in the liquid beer. A glass shape which promotes foaming may prevent some of the most important flavour molecules from escaping and reaching the drinker鈥檚 taste buds. 鈥淭he flavour activity of a component is linked to its ability to dissolve in the foam,鈥� says Derdelinckx.

Foam is less polar than the liquid beneath it and, because like attracts like, the foam traps the less polar flavour molecules, mainly the bitter flavours from hops and spices. Most sweet, malt and fruity flavours, which usually come from more polar molecules, remain in the liquid.

For the most popular and relatively neutral-tasting Pils-type beers, the familiar cylindrical glasses came out best in the study. Trappist beers (which include Chimay, Orval, Westwalle and Westvlederen) have a fruity taste and are traditionally served in chalice or cup-shaped glasses with a wide brim and a head of only 2 centimetres or so. These are the best shapes for these beers, say the researchers.

But brewers of other beers have got it wrong. For special beers such as Grand Cru, Cuv茅e de l鈥橦ermitage, Bi猫re du Ch芒teau, Palm and Kwak, brewers choose a thistle shape or one close to it, partly because such shapes promote foaming. These beers are 鈥渢op鈥� fermented: that is, fermented at room temperature (20 掳C to 25 掳C) to produce a lot of yeast and carbon dioxide. Like the stronger Trappist beers, they contain a lot of acetate esters, which give them their characteristic fruity aroma. But the researchers found that in thistle-shaped glasses most of these esters are trapped beneath the foam head, which in these beers is usually 3 to 4 centimetres deep.

The flavours in the foam were more likely to be the molecules responsible for 鈥渃heesy鈥� flavours reminiscent of pale ale. 鈥淔or these beers, glasses should be larger, with a large neck, not a narrow brim,鈥� says Derdelinckx. This would reduce the size of the head, allowing the proper combination of flavour molecules to emerge. 鈥淎bbey鈥� beers such as Leffe, Grimbergen and Maresous, served in glasses that are a cross between a chalice and a thistle, emerged as borderline cases. For these, Derdelinckx advises as large a brim as possible.

The results are part of a new study by the Leuven researchers of how foam affects flavour. They want to know, for instance, which flavours dominate the initial taste because competing flavours are held back in the liquid, and which dominate simply because there are more of them. The researchers remain philosophical about whether brewers will change the shape of their glasses to suit their beers: 鈥淭radition is too strong,鈥� says Derdelinckx.

Researchers at St Thomas鈥� Hospital in London led by Jonathan Powell, and physicists at the University of Oxford, have now devised a way of telling the difference. The procedure relies on a sophisticated piece of laboratory equipment, but the researchers are confident that it can be developed as a routine way of detecting exposure to toxic metals up to several years after it occurred.

Hair analysis relies on the fact that the hair protein, keratin, binds to certain ions. In conventional hair analysis, the hair is first washed in an attempt to remove any surface contamination, before being chopped into tiny pieces. Mass spectrometry is then used to determine what substances are present.

Powell and his colleagues have instead analysed hairs using the nuclear probe microscope at Oxford University. This fires a beam of protons at a sample and can be used to detect minute quantities of metals by recording the X-rays emitted as a result. When they are hit by protons, metal ions radiate X-rays at characteristic wavelengths.

Scanning along the length of the hair allowed the researchers to see where peaks of toxin concentration occurred. In theory, this could be used to date exposure to a toxic metal. And by looking at cross sections of hair, Powell and his colleagues were able to tell whether the metal lay on the outside or within the hair, and map its concentration to an accuracy of several parts per million. This showed that merely washing a hair does not remove all of the metal ions contaminating its surface. 鈥淚t鈥檚 really the first time we鈥檝e been able to look at hair properly,鈥� says Powell.

The new technique has revealed both the strengths and weaknesses of hair analysis. Powell鈥檚 team found that the technique accurately reflected exposure to lead, for instance, but not copper.

These variable results throw doubt on the claims of some researchers that hair analysis could be used as a sensitive probe to reveal people鈥檚 nutritional status. Nevertheless, Powell says that the new technique will be very useful for detecting whether people have been exposed to certain toxic metals through contaminated drinking water supplies.

Indeed, the researchers developed the technique as part of an investigation of the Camelford water pollution incident of 1988, when drinking water in the Cornish village became highly acidic after being contaminated with aluminium sulphate. Powell and his colleagues wanted to find out whether these acidic conditions could have caused other toxic metals, such as lead or uranium, to be released from scale deposits in local water pipes.

The hair analysis revealed that people who had drunk the polluted water suffered a short, sharp exposure to lead, but not enough to cause poisoning or any known long-term effects. No uranium was detected in the hair of Camelford residents, even though it was present in the scale lining the village鈥檚 water pipes.

At present, the Oxford nuclear probe microscope is the only one in Britain. But Powell says that smaller devices to produce beams of protons are now being developed. The researchers describe the new hair analysis technique in the March issue of The Analyst (vol 120, pp783-798).

Remember Monopoly? I do. Never a Christmas but there were vitriolic
arguments with my enterprising brother, who cheated his way every year to
an empire on the Old Kent Road. But it could all have been so different.
Forget the fun and money 鈥� we were sadly deprived of a chemical education.
If only we had passed Go and collected, not 拢200, but 50 neut-rons,
with which to buy a chemical element as our counters marched round a colourful
board of symbols ranging from hydrogen to astatine. And instead of that
sordid cash, we could have traded protons for a helium balloon ride to a
Group VIIB metal of our choice. Sound exciting? That essential gift we never
had was ElementO, the board game that educates while it entertains. Desperate
chemistry teachers and boffins, this is for you.

By the end of an hour my young opponent had grasped that chemical symbols
often bear little resemblance to their names and that chemistry involves
adding up. Well, you have to be deeply suspicious of a game that has a blurb
listing not only 鈥榦bject鈥� but 鈥榩urpose鈥�. This Christmas, I鈥檒l be trying
out the latest computer games.

The cottage was discovered during a survey, funded by the Lever-hulme
Trust, of 142 medieval houses. The researchers identified it as the most
unusual of a group of Oxfordshire houses dating from before 1350. Most medieval
houses in the Midlands and south of England are 15th century.

To date timbers, researchers take pencil-sized cores from the outside
to the centre of the timber and measure the widths of the rings, which vary
from year to year. These are compared with a 鈥榤aster sequence鈥� to give a
date for the outermost ring.

The master sequence is made by matching a long series of rings from
timbers 鈥� as many as 200 rings from each. Their age is deduced in turn by
working backwards from trees felled on known dates.

Using computer matching at the Nottingham Tree Ring Dating Laboratory,
the researchers compared timbers from the Mapledurham cottage with a master
sequence that runs from 1100 to the mid-eighteenth century and is precise
to within a year. The date 鈥� 1335 鈥� is the date the trees used to make the
timbers were felled. Historians know from the way the peasant economy worked
that the timber would have been used immediately, without being stored or
seasoned.

Architectural historians can tell from the cottage鈥檚 construction that
it was not a manor house. For example, the roof is supported by two timbers
which form an upturned curved 鈥榁鈥� shape. Manor houses tended to have a more
sophisticated structure in which the two timbers were braced by a cross
beam to form an 鈥楢鈥� shape. The modest quality of the carpentry also betrays
the building鈥檚 lowly status.

Nat Alcock of the University of Warwick said it was probably size, rather
than quality of construction, that ensured the house鈥檚 survival. 鈥楢lthough
its construction was simple it was well enough built to survive 650 years
and fortunately was just large enough for conversion by the insertion of
upper rooms to be usable in a modern village.

(see Graphic)
For most of this century, chemists believed that they knew the molecular
structure of mauveine, the world鈥檚 first synthetic dye. But now two British
chemists say the accepted structure is wrong.

Mauveine is made by using potassium dichromate to oxidise the organic
molecules aniline and toluidine. The product is a greenish crystalline
substance which dyes fabric a regal purple. It became very popular as a
colour for clothes in the past century, and was even used to colour the
first postage stamp. The discovery of mauveine by William Henry Perkin in
1856 is widely regarded as the beginning of the organic chemicals industry.

In the early part of this century, chemists deduced the molecule鈥檚 basic
structure from Perkin鈥檚 starting materials. Otto Meth-Cohn and his student
Mandy Smith of the University of Sunderland say this structure can be traced
back to the 7th edition of a handbook of dyestuffs, published in Leipzig in
1924 by a German chemist Gustav Schultz. Since then, the structure has
passed into the literature, including Chemical Abstracts, a standard
reference work for chemists.

Meth-Cohn and Smith analysed samples of Perkin鈥檚 original dye taken from
collections held in the British Museum and at the chemicals manufacturer
ICI. Using various kinds of spectroscopy, they discovered that neither of
its two main components fitted Schultz鈥檚 structure. The positions of several
methyl (CH₃) groups on the carbon rings was incorrect.FIG-mg18833201.GIF

No one knows how Schultz arrived at his structure. 鈥業 think he invented it,鈥�
says Meth-Cohn. Interestingly, Schultz鈥檚 structure never reached the pages
of Beilstein, the respected German reference work.

In practical terms, the error is of little importance. The discrepancy in
structure is not dramatic enough to have made much difference to mauveine鈥檚
colourful chemistry.

Nobel prizes do not tell the whole story, but this volume is a useful
reference work for any chemist with a sense of context. It neatly
illustrates how even 鈥榗lassical鈥� areas are expanding and overlapping in all
directions: as Roald Hoffmann was building bridges between inorganic and
organic chemistry, Jean-Marie Lehn was redefining the limits of molecular
interactions.

Disparate but disappointingly brief biographical sketches of the men who won
the prizes give few hints of how to become a Nobel prizewinner. But the
volume does inspire speculation about what molecules might feature in the
next one in the series. Will buckyballs make it at last? Nitric oxide must
be a strong contender. The borders with biology look likely to stay open for
a while yet.

Embarrassed biographers from the 18th century onwards have explained
away these alchemical leanings as 鈥榯he result of nervous collapse that crippled
his mental faculties鈥� or as activities that 鈥榬elieved the fatigue of severer
studies鈥�. In 1946 the economist John Maynard Keynes described him, notoriously,
as 鈥榯he last of the magicians鈥�. But according to Piyo Rattansi, professor
of history and philosophy of science at University College London, Newton鈥檚
interest in alchemy was crucial to the development of his law of gravitation.

鈥楢lchemy was not a mere curiosity,鈥� Rattansi told the BA. 鈥業t freed
him from the straitjacket of mechanistic theory.鈥� Contemporary European
intellectuals had difficulty accepting Newton鈥檚 theory 鈥� even though the
mathematics worked beautifully 鈥� because it seemed to resurrect the discredited
theory of attraction between distant objects. They regarded explanations
not based on their strict criteria of 鈥榩ush and pull鈥� as unscientific.

Rattansi argues that Newton was opportunistic. 鈥楬e had a foot in both
camps 鈥� one in the alchemists鈥�, and one in the mechanists鈥�.鈥�

Such glimpses into life behind the bare facts about two chemical elements
are to be found in the first of six programmes in a series called The Human
Element*, which attempts to put a little human interest into chemistry.
The other five programmes will ramble briefly through the periodic table
to find out whether Napoleon was indeed poisoned by the arsenic in his wallpaper
and how nitrogen lost the British showjumping team the Aga Khan Cup. They
investigate the link between oxygen and an exploding ship, and the controversy
sulphur caused in an ancient Dutch church. Finally, Carl Djerassi explores
the links between carbon, contraception and art.

I was intrigued by the idea of the series and impressed by the glossy
booklet that accompanies it. But I found it rather disjointed. If its theme
is the human element in chemistry, there are two things missing. The periodic
table 鈥� it is the chemist鈥檚 alphabet 鈥� should have put in an appearance
at the beginning. Then there is the unanswered question of why anyone finds
elements so interesting in the first place. Without some attempt to answer
this, the human element in some of the stories seems almost incidental.
The chemical elements are all around us and the programmes do not convey
a strong impression of how and why people set out to investigate them.

Still, the series is entertaining, and it certainly whets the appetite.
I made an immediate mental note to find out whether Meitner鈥檚 diaries are
in print. You might discover that chemistry is fascinating, but don鈥檛 expect
to find out what it is like to be a chemist.

*Saturdays on BBC₂ at 6 pm from 16 May, repeated on Sundays
at 11.30 pm on BBC₁ from 24 May.