Universal Foam by Sidney Perkowitz, Walker, $24.00, ISBN
0802713572
WHY do foams make shaving easier, cushions squishier, firefighting safer,
wound repair quicker and drug production cheaper? What is an aerogel and why
does it hold world records for 14 different physical properties? Sidney
Perkowitz has the answers to these and many other foam puzzles in Universal
Foam.
So what exactly is a foam? Well, essentially it鈥檚 a foam as an assembly of
bubbles, or 鈥渃ells鈥�, in which the cell walls are made of a solid or a liquid and
the centre of each cell is full of gas. This is straightforward, but delving a
little deeper leads to unexpected complexities. For example, the most likely
shape for each cell should be the one with the minimal surface area compatible
with the requirement that they 鈥渢essellate鈥� (fit together in space). This shape
clearly lies somewhere between a sphere and a cube, but identifying it precisely
has proved a stiff challenge for mathematicians and computer programmers.
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Topics such as tessellation are a potential turn-off for many of the target
readership of this popular science book, but Perkowitz has a very sure hand as
he takes us through the ways in which foams can be created, characterised and
used.
Along the way, he reveals many interesting snippets of information, set in
the context of how foams behave. Quite a few of these relate to edible foams. In
fact, this book should be required reading for all cooks. Perhaps most of them
already know that even a single drop of egg yolk accidentally mixed in with the
egg white will ruin a meringue: if they read the book they鈥檒l find out why.
Perkovitz covers the obvious edible foam topics well, such as the history and
science of bread and beer. He surprises readers by including the less obvious
ones too. Do you know the difference between a baked Alaska and a frozen
Florida? Both depend on the thermal properties of foams. He smuggles in the
secrets of Coca-Cola production, adding that carbon dioxide is injected into the
drink at twice the pressure in a car tyre. You鈥檒l also learn that traditional
champagne glasses were modelled on the shape of Marie Antoinette鈥檚 breasts, but
that they are being supplanted by a shape much better suited to retaining the
effervescent foam 鈥渉ead鈥� for a few minutes. And not only is the difference
between latte and cappuccino coffee explained, but also the linguistic origins
of these names.
Is Universal Foam a bit on the 鈥渇rothy鈥� side? Well, not really.
While it clearly isn鈥檛 intended to be a scholarly tome, and it can certainly be
read and appreciated by general readers, Perkowitz has added material to
interest people from a range of scientific disciplines. From the pioneering work
of Belgian physicist Joseph Plateau in the 19th century to recent topological
analyses and high-tech experimental investigations, you鈥檒l find a lot about the
science of foams. Equations and graphs are entirely absent, but the material is
solidly based on scientific principles. Perkowitz鈥檚 excellent bibliography is a
bonus, directing the reader to key publications in the field.
He also has a highly developed historical perspective. With his breadth of
interests and knowledge illuminating every historical reference, he explains the
contributions to foam science made by a galaxy of star scientists from Newton,
Hooke, Priestley, Lavoisier, Kelvin and von Neumann, to Crick and Watson. There
are surprises: here you鈥檒l find Pliny the Elder and Aristotle rubbing shoulders
with Darwin, Einstein, Planck and Hubble.
His wide-ranging knowledge also shows in the topics he covers, from the
optical properties of sea foams and their relevance to the Beaufort scale, to
the structure of galaxies. There are insights here that will be appreciated by
sailors, surfers and divers, not to mention geologists, biologists, astronomers,
chemists, physicists, medics and materials scientists.
It鈥檚 not a perfect book: for example, he suggests that the superior stability
of aluminium-based foams at very high temperatures, compared with solid
aluminium, is due to the lower thermal conductivity of foamed aluminium. While
this may play a role under some circumstances, more important is the tendency
for its oxidation product (alumina) to form rigid open networks within the foam.
This inhibits the rapid release of the heat associated with this reaction, and
melting, which is so dangerous in solid aluminium. And a pedant鈥檚 eyebrows might
rise at the breadth of the author鈥檚 interpretation of what constitutes a foam.
However, this is nit-picking.
Taken overall, Perkovitz鈥檚 book is highly readable and entertaining, with a
wealth of interesting information set in an accurate and sound scientific
framework.
Universal Foam deserves cult status. There鈥檚 ample material here for
impressing at dinner parties, partly because much of it can be linked to what鈥檚
on the table. Buy it and read it through: you won鈥檛 be disappointed and you鈥檒l
start looking out for the foams which surround us and play such an important
part in our lives.