Today in History – March 8, 1775 – Priestley discovers oxygen through experiments with mice. Oxygen was independently discovered in the 1770′s; the most famous names associated with this discovery are Joseph Priestley, Carl Wilhelm Scheele and Antoine Lavoisier. Credit is usually given to Joseph Priestley as he had the first publication on the discovery (“Experiments and Observations on Different Kinds of Air”). Earlier Carl Wilhelm Scheele discovered that red-hot manganese oxide (MnO₂) produces a gas he called “fire air”. In 1774 Priestly reproduced an earlier experiment by pharmacist Pierre Bayen in which heated mercury oxides produced a discharge of gas and a loss of mass. Lavoisier also performed a similar experiment and made note of the gas in his notebook. On March 8, 1775, Priestley demonstrated with mice that sealed containers of the new gas could support life longer than atmospheric gas. He experimented on himself and said that he felt “peculiarly light and easy for some time afterwards. Who can tell but that, in time, this pure air may become a fashionable article in luxury.” He speculated that the gas was “dephlogisticated air”, using what would soon be a discredited phlogiston theory. The name “oxygen” was actually coined by Lavoisier and he is credited with best appreciating the discovery’s significance and developing a systematic theory of combustion.

For more information see the Engineering Pathway’s educational resources on Joseph Priestley and the discovery of oxygen. For related curricular resources, visit the Chemical, Biochemical, Biomolecular Engineering disciplinary communities.