The Bell Jar (Knobbed), S.G. is a laboratory glass apparatus used to create a sealed or controlled environment for various scientific experiments. It is manufactured from clear soda glass (S.G.), allowing easy observation of the materials or reactions placed inside the jar.The bell jar features a dome-shaped design with a knob on the top, which provides convenient handling and easy lifting during experimental procedures. It is commonly placed on a vacuum plate or base to conduct vacuum demonstrations, air pressure experiments, and other laboratory studies.