We turn to an oddity in the world of chemistry that became more widely known in the 1980s: non-equilibrium thermodynamics, and especially oscillating reactions. A couple of examples were known in the 19th century, but the first model for how such reactions might go was created by Alfred Lotka and Vito Volterra early in the 20th century. We hear about Liebhafsky and Bray's oscillating reaction, and then Boris Belousov's reaction, studied further by Anatol Zhabotinsky. Around this time, Ilya Prigogine also started to research the general topic of non-equilibrium thermodynamics, which helps to explain such oscillating reactions. By the 1960s and 1970s, scientists began explaining the Belousov-Zhabotinsky reaction via the Brusselator, FKN, and Oregonator mechanisms. We end with the first attempts to devise new oscillating reactions, and how these reactions help to explain fingerprints, zebra stripes, leopard spots, and other biological structures. Become my Patreon supporter, and download a supplemental sheet with diagrams of some of the topics I discuss.Support the show Support my podcast at https://www.patreon.com/thehistoryofchemistry Tell me how your life relates to chemistry! E-mail me at steve@historyofchem.com Get my book, O Mg! How Chemistry Came to Be, from World Scientific Publishing, https://www.worldscientific.com/worldscibooks/10.1142/12670#t=aboutBook