The bubble thermometer

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Le thermomètre à bulle

Long before our current engineers pushed technology ever further and continually improved this essential measuring instrument allowing us to check the temperature that is the digital thermometer, members of the Accademia del Cimento in Florence invented the Galileo's thermometer (in honor of the well-known physicist who invented the thermoscope). This thermometer, whose operation is based on Archimedes' thrust, is a small thermodynamic treasure and, today, a real decorative gem. THE measuring device experts what are the advisors of Thermometre.fr, could not miss the bubble thermometer in their guide…

What is a bubble thermometer? 📖

There is no better way to read the temperature than on a bubble thermometer. Unlike the mercury thermometer consisting only of a narrow bulb containing mercury which expands and contracts depending on room temperature or outside temperature, the Galileo's thermometer is much more complex.

Indeed, this bubble thermometer allows you to take the temperature of a room, i.e. the ambient temperature of your living room for example. The bubble thermometer has a sealed glass column. It also contains a transparent liquid, which generally turns out to be mineral oil. This glass tube contains different spheres of blown glass, each filled with a colored liquid (often alcohol or water and coloring) and weighted by a metal medallion on which is engraved a temperature value displayed in degrees Celsius or Fahrenheit depending on the country. These little glass balls sink or float in their surrounding liquid depending on time and temperature, slowly and gracefully (yes, a thermometer can be graceful).

How does the bubble thermometer work? ⚙️

The Galileo's thermometer works on the principle of Archimedes' thrust. But what is Archimedes' thrust? you tell us! Also called the buoyancy principle, Archimedes' buoyancy determines whether an object floats or sinks in a liquid. And even steel boats can float. The only factor that determines whether an object floats or sinks in a liquid is the density of the object relative to the density of the liquid it is placed in:

  • if the density of the object is greater than the density of the liquid, the object sinks;
  • if the density is lower, the object rises towards the surface;
  • if the density of the object is equal to the density of the liquid, the object floats.

The bubble thermometer, as we said previously, is made up of several glass ampoules containing different liquids. Each of them has its own properties. Depending on the temperature, they modify the density of the liquid and the flotation increases or decreases. Each glass bulb has an assigned temperature, making it easy to control the temperature.

Have you understood how this pretty thermometer works? What if you did a little experiment? 😉

The experience of Thermometre.fr advisors with the bubble thermometer ⚗️

Whether you are a physics professor in a college or simply curious, we suggest you carry out a little experiment that will allow you to easily understand how the bubble thermometer works.

Take a Galilean thermometer and place next to it a small vial of blue-colored water, into which you immerse the external probe of a electronic thermometer. Put these thermometers in a room with a low temperature, for example 18°C, then gradually increase the temperature of the room.

You then observe the glass spheres descend and rise depending on the temperature displayed on the LCD screen of your digital thermometer.

Other types of thermometer

It is still important to remember several details regarding the bubble thermometer. It is neither fast nor precise. This cannot be used to check the outside temperature, especially at very low or very high temperatures, at the risk of being disrupted by bad weather. This is why, the professional thermometer advisorss the Thermometre.fr strongly recommend that you discover all of the thermometers best suited to your use or more broadly, to your sector of activity.

In fact, you will not have the same needs depending on your profession. Whether you are a scientist and working on which vaccines to store or transport at a particular temperature. Or maybe you're a pizza maker and your pizza oven needs to maintain the perfect temperature for your pizzas. Or if you are an agricultural engineer and you had to keep the compost piles of an entire city.

To go further, know all of the different types of thermometers that exist, our temperature sensor advisors have looked into a whole bunch of topics that might interest you. Do not hesitate to look at the different types of thermometers on the Mag’ from Thermometer.fr:

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