Bell jar

Bell jar

Early 20th century bell jar with a vacuum pump
Uses	Enclosing objects, containing gases or a vacuum

A bell jar is a glass jar, similar in shape to a bell (i.e. in its best-known form it is open at the bottom, while its top and sides together are a single piece), and can be manufactured from a variety of materials (ranging from glass to different types of metals). Bell jars are often used in laboratories to form and contain a vacuum. It is a common science apparatus used in experiments.^[1] Bell jars have a limited ability to create strong vacuums; vacuum chambers are available when higher performance is needed. They have been used to demonstrate the effect of vacuum on sound propagation.

In addition to their scientific applications, bell jars may also serve as display cases or transparent dust covers. In these situations, the bell jar is not usually placed under vacuum.