Letter, from Antoni van Leeuwenhoek to Henry Oldenburg, dated at Delft Signed autograph Observations of the crystallisation of salts and infusions; observations of vinegar, Spanish soap and common soap, aqua fortis (nitric acid and sulphuric acid), pepper, mustard; observations of the globules in the bile of different species of fish; further observations of the optic nerve of cod and cows; observations of cod's roe; objections to Francis Redi's figure of a louse Figures of the crystallisation of salts attached. Other diagrams mentioned in the letter are not attached. Partial translation see EL/L1/12 Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, part 1, p 230 For summary see 'The correspondence of Henry Oldenburg', ed and trans by A Rupert Hall & Marie Boas Hall, vol 11, p 175 11 February 1675