Chemistry through time

Put your knowledge of Chemistry to the test with these history-themed questions from St John’s Chemistry Tutor Professor Richard Compton and his research group.

Q: The Ashmolean Museum in Oxford is one of the renowned museums owned by Oxford University. Here you can see galleries full of paintings and sculptures made of white marble or blackened bronze, from ancient Egyptian times to the Classical period in Greece and through to the late Roman period. However, antiquity was not black and white, it was much more colourful than we imagine. With time, this colour has faded or completely disappeared, leaving us with a false impression of a monochrome antiquity. Where colour has been lost, is it possible to realistically reconstruct the original look? Can you find the chemistry to help today’s museum conservationist colouring the past?

Q: A ‘Storm glass’ is a sealed glass tube containing a camphor–ethanol solution with aqueous NH4Cl and KNO3 solution. In 19th century England, the pattern and quantity of the crystals formed were observed and interpreted as a weather forecasting tool. The following predictions about the weather were made depending on the appearance of crystals; the growth dendrites filling the glass tube suggested cold and stormy weather, melting crystals suggested warm weather, few crystals in a clear solution suggested fine and dry weather, floating star-like crystals suggested cold weather, and floating feather-like crystals suggested rain. Why can the storm glass predict weather?