Editing Joseph Priestley (section)

===Founder of British Unitarianism===
{{See also|History of Unitarianism}}
When Priestley's friend [[Theophilus Lindsey]] decided to found a new Christian denomination that would not restrict its members' beliefs, Priestley and others hurried to his aid. On 17 April 1774, Lindsey held the first [[Unitarianism|Unitarian]] service in Britain, at the newly formed [[Essex Street Chapel]] in London; he had even designed his own liturgy, of which many were critical. Priestley defended his friend in the pamphlet ''Letter to a Layman, on the Subject of the Rev. Mr. Lindsey's Proposal for a Reformed English Church'' (1774),<ref>Priestley, Joseph. ''Letter to a Layman, on the Subject of the Rev. Mr. Lindsey's Proposal for a Reformed English Church''. London: Printed for J. Wilkie, 1774.</ref> claiming that only the form of worship had been altered, not its substance, and attacking those who followed religion as a fashion. Priestley attended Lindsey's church regularly in the 1770s and occasionally preached there.<ref>Schofield (2004), 26–28; Jackson, 124; Gibbs, 88–89; Holt, 56–64.</ref> He continued to support institutionalised Unitarianism for the rest of his life, writing several ''Defenses'' of Unitarianism and encouraging the foundation of new Unitarian chapels throughout Britain and the United States.<ref>Schofield (2004), 225, 236–38.</ref>

[[File:Priestley Joseph pneumatic trough.jpg|thumb|Equipment used by Priestley in his experiments on gases, 1775|alt=Engraving of assorted scientific equipment, such as a pneumatic trough. A dead mouse rests under one glass canister.]]
[[File:Priestly-2.jpg|alt=Title page to volume I of Experiments and Observations on Different Kinds of Air (1774)|thumb|upright|Title page to volume I of ''Experiments and Observations on Different Kinds of Air'' (1774)]]