Using a Liquid-in-Glass Thermometer

  • Treat the instrument with care - the glass bulb is easily broken.
  • Immerse the bulb in the substance and wait until the thread in the tube settles to a steady value - it takes time for a liquid to expand or contract.
  • It is best to keep the bulb immersed all of the time otherwise the thermometer will start to adjust to room temperature - if you have to leave it standing in the container be careful to check the stability of the apparatus before you let go of it - otherwise make sure that it has time to adjust before you take the next reading!
  • Take care - while holding a thermometer as you heat a container of liquid you have to make sure you do not burn yourself or set fire to the sleeve of your labcoat.
  • Stir gently for about ten seconds before you intend to take the reading - some parts may be hotter or cooler than others
  • Take the reading at eye level (care if heating not to set your hair alight!)
  • Double check that you understand what each division on the scale represents and get a friend to check the reading.