|Description||Nos 1 to 30. Letters from Joseph Priestley to Josiah Wedgwood and one from Wedgwood to Priestley, 1780-1791. |
Nos 31 to 33. Letters from Joseph Priestley to Thomas Wedgwood, 1792.
The letters between Priestley and the Wedgwoods chiefly concern Priestley's experiments with different gases (or "airs" as Priestley refers to them). Josiah Wedgwood supplied Priestley with experimental apparatus (tubes, retorts etc) and received these letters describing Priestley's experiments.
Priestley was a supporter of the phlogiston theory. Namely, that in all flammable materials there is present phlogiston, a substance without colour, odor, taste, or weight that is given off in burning. “Phlogisticated” substances are those that contain phlogiston and, on being burned, are “dephlogisticated.” This theory was refuted by Antoine Lavoisier, who re-interpreted and re-examined Priestley's work and is now credited with the discovery of Oxygen (which Priestley had discovered in 1774 but didn't realise it was Oxygen, naming the substance "dephlogisticated air").
MM/5/1-33 date from after Lavoisier's naming of Oxygen and show Priestley attempting to defend the phlogiston theory. There are also descriptions of Priestley's experiments which led to the discovery of the chemical composition of water. Priestley mixed "inflammable air" (ie hydrogen) with dephlogisticated air (oxygen) in a flask, to which he applied an electric spark. The inside of the flask became covered with moisture. Whilst Henry Cavendish and James Watt independently repeated the experiment, it was Antoine Lavoisier who was first to register the result that water was not an element with an independent body (namely the French Academy).
Nos 34 to 37. Letters of Augustus Duke of Sussex, FRS, 1830-1837.
No. 38. Copy of letter of James Watt, 1783.
Nos 40-50. Letters of Edmund Halley, Brook Taylor, Philippe Nande and B de Fontenelle, 1696-1723.
Letters from Halley to Isaac Newton and describe Halley's employment at Chester Mint.
No. 51 Letter of Jean Baptiste Joseph Delambre, 1811.
No. 52 Letter of Daniel Colwall, 1674.
Nos. 53-54 About Louis Pasteur and the Copley Medal, 1874