Priestley's apparatus. Diagram after an engraving showing various pieces of experimental apparatus used by Joseph Priestley (1733-1804). Most of these are troughs and bell jars with which he would isolate and store gases. Some jars would contain plants or mice to see what effect each gas had upon them. Famous for the discovery of oxygen, Priestley's work is contained in the three-volume Experiments and Observations on Different Kinds of Air published in London, 1774-7.