How to Use a Mercury Thermometer

By Max. D Gray. Updated: January 16, 2017
How to Use a Mercury Thermometer

The mercury thermometer is a classic design for temperature measurement still used by many families. Although currently there are digital thermometers this form of temperature measurement is still very much in demand, in addition to being very simple to use. If you are not sure how to use it in this OneHowTo article we explain how to use a mercury thermometer.

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Steps to follow:

Such thermometers have mercury inside. This is a substance which expands when heated and accurately measures the body temperature of who is using the thermometer. They are marked with numbers and in the middle have a thin line that will be responsible for marking the temperature value.

How to Use a Mercury Thermometer - Step 1

Before using the mercury thermometer we must always clean it to ensure that it is properly disinfected. For this you must use a cotton ball soaked in alcohol and wipe the thermometer bulb, i.e. the metal part which comes into contact with the body to measure the temperature.


Once clean we are ready to measure the temperature. Start by taking the thermometer from the opposite side of the bulb and shake it vigorously. This will help lower any residual mercury that may remain in the thermometer, thus ensuring that the indicated temperature is reliable.

This type of thermometer can be used in three areas of the body:

  • Under the tongue, recommended for adults and teenagers.
  • In the armpit.
  • In the rectal area, the area that offers greatest temperature accuracy. This is recommended in the case of infants or small children.
How to Use a Mercury Thermometer - Step 3

Once you have decided on which area you will use the thermometer place it there and wait three minutes, time necessary for the mercury to rise and indicate the temperature. We recommend keeping time to avoid removing the thermometer before it is due.


After this time remove the thermometer and check the temperature to which reaches the centre line has risen, this will indicate body heat. When our temperature exceeds 37 degrees we are considered to have fever. If it exceeds 40 degrees you should see a doctor urgently.


Once you are done with using the mercury thermometer it is very important to shake down the substance, disinfect it with alcohol and store it safely. If you use the thermometer in the rectum it should only be used in this area from now on. You can purchase another thermometer for measuring the temperature under the tongue.

How to Use a Mercury Thermometer - Step 6

Bear in mind that these thermometers have mercury inside, a substance that can be dangerous if the thermometer breaks. If the thermometer breaks you should NEVER:

  • Vacuum the mercury, as the substance would go into the air.
  • Use a broom to clean up the mercury, as this would only break the mercury into smaller drops.
  • Pour it down the drain, as it is a highly polluting chemical substance.
  • Walk on it or touch it with a piece of clothing, as you could spread the mercury.

If your mercury thermometer this is what you should do:

  • Make sure everyone leaves the area where the thermometer has broken, even pets.
  • Put on latex gloves.
  • Clean all the small pieces of glass.
  • Use a cardboard to gather all the mercury beads.
  • Put the beads inside a bag and bring this bag to the local waste facility.

This article is merely informative, oneHOWTO does not have the authority to prescribe any medical treatments or create a diagnosis. We invite you to visit your doctor if you have any type of condition or pain.

If you want to read similar articles to How to Use a Mercury Thermometer, we recommend you visit our Family health category.

Write a comment

What did you think of this article?
Brother Seraphim
Clean - disinfect it - with alcohol - isopropyl alcohol, rubbing alcohol (not alcohol for drinking); clean not only the metal bulb end, but most of the rest as well, which will also be in the mouth.
Am grateful to find the 3 minutes, as I'd forgotten and become unsure: thank you!
judy wavers
Where can I order a mercury thermometer?
Brother Seraphim
You can order a mercury thermometer online at Amazon, and probably elsewhere, too. If you would, try a search for "mercury thermometer mouth" and see. Not sure, but might still find them available at drug stores (in Britain, at the chemists), or at the pharmacies and, if they don't stock them, perhaps they'd order them for you.
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