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were especially interested in the properties of air, because steam engines were then revolutioniz- ing transportation, and the phe- nomenon of combustion was vitally important to that field.

Early Discoveries

Joseph Priestley moved to America to support the Revolution there.

The story of oxygen’s dis- covery is marked by some con-

fusion and controversy. When science historians recount the tale, they mention three men—Joseph Priestley (1733–1804), Carl W. Scheele (1742–1786), and Antoine Lavoisier (1743–1794). Each of these men is usually given some level of credit. In about 1772, Scheele, a Swedish apothecary , found that sev- eral compounds, including silver carbonate and potassium nitrate, all gave off the same gas when heated. An excited Scheele called the mystery gas “fire air,” because it produced sparks when it came into contact with charcoal dust. Proving it never pays to procrastinate,

13

The Chemistry of Everyday Elements