Joseph Priestley's Last Laboratory: Oxygen's Father in Exile

The brick house on Priestley Avenue in Northumberland, Pennsylvania, looks modest from the road. But inside, one of the greatest scientific minds of the eighteenth century spent his final years, continuing experiments that had already changed how humanity understood the air it breathes.

Joseph Priestley was born in Yorkshire, England, in seventeen thirty-three. By seventeen seventy-four he had isolated a remarkable gas, one that made flames burn hotter and let mice live longer in sealed containers. He called it dephlogisticated air. The French chemist Antoine Lavoisier would later name it oxygen. Priestley himself never quite accepted Lavoisier's framework, clinging instead to the old phlogiston theory that oxygen had essentially destroyed. He discovered the gas but could not follow where it led. That tension defines him: a man who opened a door and refused to walk through it.

Outside the laboratory, Priestley was dangerous. He was a Unitarian minister who openly supported the American Revolution and then the French. On July fourteenth, seventeen ninety-one, the second anniversary of Bastille Day, a Birmingham mob stoked by government sympathizers set fire to his home, his church, and his laboratory. The rioters shouted Church and King as they burned eleven years of notebooks. Priestley fled, eventually to London, and then in seventeen ninety-four across the Atlantic entirely.

He chose Northumberland, Pennsylvania, a small river town at the confluence of the two main branches of the Susquehanna. His sons had already settled nearby. He built the Georgian house here between seventeen ninety-four and seventeen ninety-eight, designing a proper laboratory on the first floor where he could keep working. He corresponded with Thomas Jefferson, who sought his advice on the design of a future Virginia university, ideas Jefferson drew on years later in founding the University of Virginia.

He died here on February sixth, eighteen oh four, and is buried in Northumberland's Riverview Cemetery. The house is now a Pennsylvania state historic site. The laboratory has been carefully restored, its wooden shelves lined with the kinds of glass apparatus Priestley used. Outside, the Susquehanna rolls past, indifferent. Inside, there is still something in the air.