bell jar(n = noun.artifact) bell glass - a bell-shaped glass cover used to protect and display delicate objects or to cover scientific apparatus or to contain gases;
is a kind of protection, protective cover, protective covering

   A glass vessel, varying in size, open at the bottom and closed at the top like a bell, and having a knob or handle at the top for lifting it. It is used for a great variety of purposes; as, with the air pump, and for holding gases, also for keeping the dust from articles exposed to view. [1913 Webster]

alarm bell, alexander bell, alexander graham bell, alexander melville bell, angelus bell, bell, bell animalcule, bell apple, bell arch, bell bearer, bell book, bell buoy, bell captain, bell cot, bell cote, bell crank, bell deck, bell founder, bell foundry, bell gable, bell glass, bell heather, bell magpie, bell metal, bell morel, bell pepper, bell process, bell push, bell ringer, bell ringing, bell seat, bell shape, bell system of control, bell tent, bell the cat, bell toad, bell tower, canopic jar, canterbury bell, church bell, cookie jar, cookie jar reserve, cooky jar, currer bell, death bell, dinner bell, diving bell, earthenware jar, electric bell, fairy bell, fire bell, heather bell, honey bell, jar, jar against, leiden jar, leyden jar, liberty bell, mason jar, melville bell, night bell, peach bell, sancte bell, school bell, sheep bell, ship's bell, shop bell, silver bell, sleigh bell, slop jar, stink bell, telephone bell, vanessa bell, warning bell, willow bell, wind bell