A Galileo thermometer operates by using a series of weighted bulbs containing a lower density liquid such as ethanol in a sealed tube of water. Based on the weight attached to the bulb each rises at a different temperature. The colouration is from a small amount of dye in each of the bulbs. The hazards are minimal, as the ethanol’s flash point is depressed by the dilution from the water. The spillage can be absorbed, double bagged and disposed of according the local authority’s wishes. The colleague may not be thrilled though.

Tom Johnson is an emergency responder at the National Chemical Emergency Centre