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Abstract. In
this paper, we revisit Fick’s original diffusion experiments and
reconstruct the geometry of his inverted funnel.
We show that Fick’s experimental approach was sound and
measurements were accurate despite his own claims to the contrary.
Using the standard modern approach, we predict Fick’s
cylindrical tube measurements with a high degree of accuracy.
We calculate that the salt reservoir at the bottom of the
inverted funnel must have been about 5 cm in height and the unreported
depth of the deepest salt concentration measurement by Fick was yet
another 3 cm above the reservoir top.
We verify the latter calculation by using Fick’s own
calculated concentration profiles and show that the modern diffusion
theory predicts the inverted funnel measurements almost as well as
those in the cylindrical tube. We
also append a translation of Fick’s discussion of diffusion in
liquids in the first edition of his three-volume monograph on Medical
Physics published in 1856, one year after his seminal Pogendorff’s
Annalen paper On Diffusion.
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