WHEN COP26 comes to Glasgow in some form later this year, the organisers must make sure that those attending or spectating at home become aware of the extraordinary contribution to the science of environmental chemistry made by a Glaswegian, Angus Smith, born in this week of 1817. You may not have heard of him, but we have all heard of acid rain, defined by National Geographic magazine thus: “Acid rain describes any form of precipitation that contains high levels of nitric and sulfuric acids. It can also occur in the form of snow, fog, and tiny bits of dry material that settle to Earth.”