Editing Fick's laws of diffusion (section)

== History ==
In 1855, physiologist Adolf Fick first reported<ref name=":0">* {{cite journal| vauthors = Fick A|journal=Annalen der Physik |year=1855 | volume=94 |issue=1 |pages=59–86 |doi=10.1002/andp.18551700105|language=de |title=Ueber Diffusion|bibcode=1855AnP...170...59F |doi-access=free }}
* {{cite journal | vauthors = Fick A |journal= The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science|year=1855 | title = On liquid diffusion |volume=10 |issue=63 |pages=30–39 |doi=10.1080/14786445508641925 }}</ref> his now well-known laws governing the transport of mass through diffusive means.  Fick's work was inspired by the earlier experiments of [[Thomas Graham (chemist)|Thomas Graham]], which fell short of proposing the fundamental laws for which Fick would become famous. Fick's law is analogous to the relationships discovered at the same epoch by other eminent scientists: [[Darcy's law]] (hydraulic flow), [[Ohm's law]] (charge transport), and [[Fourier's law]] (heat transport).

Fick's experiments (modeled on Graham's) dealt with measuring the concentrations and fluxes of salt, diffusing between two reservoirs through tubes of water. It is notable that Fick's work primarily concerned diffusion in fluids, because at the time, diffusion in solids was not considered generally possible.<ref>{{cite journal |url=http://www.uni-leipzig.de/diffusion/journal/pdf/volume2/diff_fund_2(2005)1.pdf | vauthors = Philibert J |title=One and a Half Centuries of Diffusion: Fick, Einstein, before and beyond |journal=Diffusion Fundamentals |volume=2 |year=2005 |page=1.1–1.10 | doi = 10.62721/diffusion-fundamentals.2.187 |url-status=dead |archive-url=https://web.archive.org/web/20090205030323/http://www.uni-leipzig.de/diffusion/journal/pdf/volume2/diff_fund_2(2005)1.pdf |archive-date=5 February 2009}}</ref> Today, Fick's laws form the core of our understanding of diffusion in solids, liquids, and gases (in the absence of bulk fluid motion in the latter two cases).  When a diffusion process does ''not'' follow Fick's laws (which happens in cases of diffusion through porous media and diffusion of swelling penetrants, among others),<ref>{{cite book| vauthors = Vázquez JL |year=2006 |chapter=The Porous Medium Equation |title=Mathematical Theory |publisher=Oxford Univ. Press.}}</ref><ref name=GorbanMMNP2011>{{cite journal|author1-link=Alexander Nikolaevich Gorban| vauthors = Gorban AN, Sargsyan HP, Wahab HA |year=2011 |arxiv=1012.2908|title=Quasichemical Models of Multicomponent Nonlinear Diffusion |journal= Mathematical Modelling of Natural Phenomena|volume=6 |issue=5 |pages= 184–262 |doi=10.1051/mmnp/20116509|s2cid=18961678 }}</ref> it is referred to as ''non-Fickian''.