A volumeter is a device used for measuring volume, the amount of space in three dimensions and object takes up. These devices have a number of applications, ranging from medical settings to research labs, and they are usually manufactured by suppliers of scientific instruments. For special needs, a volumeter can be fabricated for a custom order, although generic products are usually sufficient for most users.
The simplest example of a volumeter is also one of the oldest; a container filled with water. When an object is placed in the container, the volume of the object can be measured by determining how much water was displaced. As Archimedes and his bathtub demonstrated, this can be a fairly direct and easy way of measuring volume, and people can even make their own at home, using equipment like a flask or cup measure with clear markings so they can measure the degree of displacement.
Other volumeters may rely on displacement of other substances, such as solids or gases, depending on what is being measured. Liquids, solids, and gases can all be measured in a volumeter, and it is possible to collect information about specific gravity as well. Density is another characteristic people can measure with the use of a volumeter, by determining the mass and the volume of an object and dividing to find the mass per unit of volume.
The sensitivity of a volumeter varies. Some devices are carefully calibrated to the point that they can be used to measure the respiration of small living organisms, while others provide a more crude output. Sensitive devices may need to be calibrated before use and periodically tested to confirm they are still as sensitive as needed. They usually need to be handled carefully to avoid breakage or damage that might interfere with the integrity of their measurements. Volumeters can come with calibration tools like premeasured blocks so people can make sure they are performing accurately.
Volume measurements can be useful for everything from assaying precious metals to conducting pure research. Many high school science classrooms have a volumeter or teach people with simple water volumeters when units on volume, density, and other physical characteristics of objects are taught. Understanding volume and displacement is an important part of learning about everything from why boats float to how density can make some objects seem extremely heavy for their size while others can feel quite light.