Let me rather switch to surfactants, molecules with two parts: a polar head
which likes water, and an aliphatic tail which hates water. Benjamin Franklin
performed a beautiful experiment using surfactants; on a pond at Clapham
Common, he poured a small amount of oleic acid, a natural surfactant
which tends to form a dense film at the water-air interface. He measured
the volume required to cover all the pond. Knowing the area, he then knew
the height of the film, something like three nanometers in our current units.
This was to my knowledge the first measurement of the size of molecules. In
our days, when we are spoilt with exceedingly complex toys, such as nuclear
reactors or synchrotron sources, I particularly like to describe experiments
of this Franklin style to my students
-- from P. G. de Gennes's Nobel Lecture
which likes water, and an aliphatic tail which hates water. Benjamin Franklin
performed a beautiful experiment using surfactants; on a pond at Clapham
Common, he poured a small amount of oleic acid, a natural surfactant
which tends to form a dense film at the water-air interface. He measured
the volume required to cover all the pond. Knowing the area, he then knew
the height of the film, something like three nanometers in our current units.
This was to my knowledge the first measurement of the size of molecules. In
our days, when we are spoilt with exceedingly complex toys, such as nuclear
reactors or synchrotron sources, I particularly like to describe experiments
of this Franklin style to my students
-- from P. G. de Gennes's Nobel Lecture
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