540: The Invention of Air by Steven Johnson

by Gerard

540.92: Johnson, Steven. The Invention of Air: A Story of Science, Faith, Revolution, and the Birth of America. New York: Riverhead, 2008. 240 pp. ISBN 978-1-59448-401-8.

This one is simple enough: 500s are science; 540 is chemistry. A biography of a general chemist easily falls at 540.92.


Joseph Priestley was one of the brightest men of his generation. Having a natural affinity for at-home science (called natural philosophy is those days), he tinkered and experimented at every available moment. Steven Johnson’s Invention of Air chronicles Priestley’s life at it intersects the revolutions of both the American colonies and the French monarchy as well as the birth of the modern scientific method.

Because electromagnetism was all the rage during the 18th century, Priestley’s first encounters with science were electric experiments. For there he learned about Benjamin Franklin and his famous work in lightning electricity. They quickly started a correspondence that would span the remainder of their lives. When Franklin came to England (to try to hash out the whole disloyal colonists thing), he invited Priestley to join him at a meeting of scientists in London. At these meetings, he quickly understood the progress that could be gained from gathering together learned men from around the area and freely sharing experimental data and theories. Almost everywhere he went, an organization existed.

Sometime later, he was asked by Lord Shelburne to tutor his children and maintain his library. In return Priestley and family would be compensated with free lodging and plenty of leisure time to conduct more experiments. By this time, he was working on experiments concerning the “phlogiston theory”—that the air we breathe is composed in part by a material called phlogiston which allows flames to burn freely; if a flame dies out, that means the air no longer has phlogiston. By now, we all know this theory is backward, but these were different times.

In one of his experiments, he places a mint plant in a jar full of “dephlogisticated air” (actually, carbon dioxide), and found that it made the air breathable again. He discovered the carbon dioxide / oxygen transfer that occurs during photosynthesis. His next experiment was to create other kinds of air. This time, he superheated mercury ash with a magnifying lens. This reaction produced a good quantity of pure oxygen, which he breathed in and found to be very refreshing. While he continued to operate under the phlogiston paradigm, his discovery of pure air put him at the forefront of chemistry.

During his later years, he became more political and fundamentally religious while still dabbling in the scientific arts. He preached a return to pure Biblical teaching and an abolition of monarchical and dictatorial governments, opting for a more democratic environment. This radicalism led to his pilgrimage from England to the new formed United States, where he befriended both John Adams and Thomas Jefferson. He lived out the rest of his days in America, continually fighting for religious, political, and scientific aims.


Johnson’s book is not a straight forward biography, but rather a treatise on how different spheres of influence come to bear on the progress of human history. At its core is the life of Joseph Priestley, but Johnson incorporates theories of scientific revolutions, Earth System Science, the Gaia Hypothesis, and several other macro processes.

He shows how the British political landscape was fundamentally altered by the technology that allowed people to mine coal out of the northern part of the country, shifting large amount of societal wealth upward and away from the landed gentry of the south.

He also spends an interesting amount of time on how scientific discoveries can be viewed from both a long-range historical perspective and from a contemporaneous one. This dual vision gives the book a much need air of learnedness and presents the science of the 18th century in much the same light as today: as another element in the interconnected network of humanity’s knowledge.

It’s a good book, but could get a bit heady for some.