Spotted on Twitter:
My colleague Charlotte set this up before xmas…tis only just ready #chemistryrainbow #RealTimeChem @ChemistryatYork pic.twitter.com/KVsRm9VbO4
— Emma Dux (@Duxie_Em) January 6, 2014
Fantastic. Emma later noted that it’s absolutely as simple as it looks: a condenser tube filled with universal indicator solution, with acid added at one end and base at the other. Then you “wait ages” – ie. a couple of weeks.