Gutta percha bottle, 1974.
© Science Museum / Science & Society Picture Library
This bottle, shown with its stopper, was used for containing hydrofluoric acid (HF), a substance so corrosive that it attacks glas. It is 10 1/2 inches high and was used at Imperial College, London. Gutta percha is a rubber-like material from the dried sap of sapodilla trees of south-east Asia. It has the same chemical composition as natural rubber, but a different molecular structure (it is an isomer of rubber). Because of this, unlike rubber, gutta percha is hard at room temperature. This material was first exploited in Britain by Charles Hancock and Henry Bewley who set up the Gutta Percha Company in 1845.