page_title: Joseph Priestley
section_title: Natural philosopher: electricity, Optics, and carbonated water
hierarchical_section_title: Joseph Priestley / Leeds (1767–1773) / Natural philosopher: electricity, Optics, and carbonated water
caption_attribution_description: English: The History and Present State of Vision, Light, and Color, published in London 1772
context_page_description: Joseph Priestley FRS was an English chemist, natural philosopher, separatist theologian, grammarian, multi-subject educator, and liberal political theorist who published over 150 works. He has historically been credited with the discovery of oxygen, having isolated it in its gaseous state, although Carl Wilhelm Scheele and Antoine Lavoisier also have strong claims to the discovery, Scheele having discovered it in 1772, two years before Priestley.
  During his lifetime, Priestley's considerable scientific reputation rested on his invention of carbonated water, his writings on electricity, and his discovery of several "airs", the most famous being what Priestley dubbed "dephlogisticated air". However, Priestley's determination to defend phlogiston theory and to reject what would become the chemical revolution eventually left him isolated within the scientific community.
  Priestley's science was integral to his theology, and he consistently tried to fuse Enlightenment rationalism with Christian theism. In his metaphysical texts, Priestley attempted to combine theism, materialism, and determinism, a project that has been called "audacious and original".
context_section_description: Although Priestley claimed that natural philosophy was only a hobby, he took it seriously. In his History of Electricity, he described the scientist as promoting the "security and happiness of mankind". Priestley's science was eminently practical and he rarely concerned himself with theoretical questions; his model was Benjamin Franklin. When he moved to Leeds, Priestley continued his electrical and chemical experiments (the latter aided by a steady supply of carbon dioxide from a neighbouring brewery). Between 1767 and 1770, he presented five papers to the Royal Society from these initial experiments; the first four papers explored coronal discharges and other phenomena related to electrical discharge, while the fifth reported on the conductivity of charcoals from different sources. His subsequent experimental work focused on chemistry and pneumatics.
  Priestley published the first volume of his projected history of experimental philosophy, The History and Present State of Discoveries Relating to Vision, Light and Colours (referred to as his Optics), in 1772. He paid careful attention to the history of optics and presented excellent explanations of early optics experiments, but his mathematical deficiencies caused him to dismiss several important contemporary theories. Furthermore, he did not include any of the practical sections that had made his History of Electricity so useful to practising natural philosophers. Unlike his History of Electricity, it was not popular and had only one edition, although it was the only English book on the topic for 150 years. The hastily written text sold poorly; the cost of researching, writing, and publishing the Optics convinced Priestley to abandon his history of experimental philosophy.
  Priestley was considered for the position of astronomer on James Cook's second voyage to the South Seas, but was not chosen. Still, he contributed in a small way to the voyage: he provided the crew with a method for making carbonated water, which he erroneously speculated might be a cure for scurvy. He then published a pamphlet with Directions for Impregnating Water with Fixed Air (1772). Priestley did not exploit the commercial potential of carbonated water, but others such as J. J. Schweppe made fortunes from it. For his discovery of carbonated water Priestley has been labelled “the father of the soft drink”, with the beverage company Schweppes regarding him as “the father of our industry”. In 1773, the Royal Society recognised Priestley's achievements in natural philosophy by awarding him the Copley Medal.
  Priestley's friends wanted to find him a more financially secure position. In 1772, prompted by Richard Price and Benjamin Franklin, Lord Shelburne wrote to Priestley asking him to direct the education of his children and to act as his general assistant. Although Priestley was reluctant to sacrifice his ministry, he accepted the position, resigning from Mill Hill Chapel on 20 December 1772, and preaching his last sermon on 16 May 1773.
caption: Optics: The History and Present State of Vision, Light, and Colours, published in 1772, London
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