Editing Gilbert N. Lewis (section)

===Other achievements===
In 1921, Lewis was the first to propose an empirical equation describing the failure of [[strong electrolyte]]s to obey the [[law of mass action]], a problem that had perplexed physical chemists for twenty years.<ref>{{cite journal|last1=Lewis|first1=Gilbert N.|last2=Randall|first2=Merle|date=1921|title=The activity coefficient of strong electrolytes|url=https://babel.hathitrust.org/cgi/pt?id=mdp.39015018181431;view=1up;seq=1144|journal=Journal of the American Chemical Society|volume=43|issue=5|pages=1112–1154|doi=10.1021/ja01438a014|bibcode=1921JAChS..43.1112L }} The term "ionic strength" is introduced on p. 1140.</ref> His empirical equations for what he called [[ionic strength]] were later confirmed to be in accord with the [[Debye–Hückel equation]] for strong electrolytes, published in 1923.

Over the course of his career, Lewis published on many other subjects besides those mentioned in this entry, ranging from the nature of [[light]] quanta to the [[economics]] of price stabilization. In the last years of his life, Lewis and graduate student [[Michael Kasha]], his last research associate, established that [[phosphorescence]] of [[organic chemistry|organic]] molecules involves emission of light from one electron in an excited [[triplet state]] (a state in which two electrons have their [[Spin (physics)|spin vector]]s oriented in the ''same'' direction, but in different orbitals) and measured the [[paramagnetism]] of this triplet state.<ref>{{cite journal|last1=Lewis|first1=Gilbert N.|last2=Kasha|first2=M.|year=1944|title=Phosphorescence and the Triplet State|journal=Journal of the American Chemical Society|volume=66|issue=12|pages=2100–2116|doi=10.1021/ja01240a030|bibcode=1944JAChS..66.2100L }}</ref>