We talk about the development of the metric system, the units chemists use in their laboratories and calculations. We start with John Wilkins and Gabriel Mouton, who were ahead of their time in proposing a universal system of units. After the French Revolution, Talleyrand sponsored a logical set of units for France, which became the metric system. We talk about the early units of metric measurement, in both space and time. The we talk of its expansion across Europe and the world in the 19th and 20th centuries, and new official units added to make measurements and observations more consistent. We end with a brief mention of several non-metric or non-official units chemists still use.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