A [i]bell jar[/i], also known as a [i]cloche[/i] or [i]display dome[/i], is a bell-shaped vessel made usually of glass and sometimes of plastic and designed to cover objects or contain gases or a vacuum.  These objects have various purposes.  In a household setting, they were normally used as a protective dust cover for the object covered by it.  In a lab setting, they were used to trap gasses or vacuums within the container, in this setting they're specifically referred to as a [i]bell jar[/i].  In an agricultural setting, they were used to cover outdoor plants to protect them from frost, in this setting they're specifically referred to as a [i]cloche[/i].

A bell jar may or may not have a knob at the top to serve as a handle when picking it up.

h4. External links

* "Wikipedia: Bell jar":https://en.wikipedia.org/wiki/Bell_jar
* "Wikipedia: Cloche (agriculture)":https://en.wikipedia.org/wiki/Cloche_(agriculture)
bell jar