Receipted bill for a microscope, 1767.
© Science Museum / Science & Society Picture Library
A receipted bill dated 15th December, 1767, to the chemist Joseph Priestley for a microscope made by Benjamin Martin at the New Invented Visual Glases, Fleet Street, London. Priestley (1733-1804) discovered various gaseous elements and compounds and, in an experiment in 1774, obtained a gas which he named 'dephlogisticated air'. This was in fact oxygen, although it was not named thus until the French chemist Lavoisier (1743-1794) repeated Priestley's experiment.