"Experiments and Observations on Different Kinds of Air" by Joseph Priestley is a six-volume work that reports a series of his experiments on "airs" or gases, most notably his discovery of the oxygen gas. While working as a companion for Lord Shelburne, Priestley had a great deal of free time to engage in scientific investigations. The Earl even set up a laboratory for him. Priestley's experiments during his years in Calne were almost entirely confined to "airs" and from this work emerged these most important scientific texts