As with all the exhibits in the museum, Sigrid Keller also knows the history of her favourite pieces, glass tubes joined by cone cuts: "Until the 19th century, chemists used cork to connect glass tubes. The problem: cork is unstable and crumbles easily. At a Christmas market in Berlin, the famous chemist Justus von Liebig observed a glassblower from Thuringia and had an idea: why not make connectors out of glass? He spoke to the artist, who then invented the cone cut. The modern laboratory glass industry was born."