Wrote Letter L-457 of 1707-07-25 to the members of the Royal Society about cinchona bark and using it as a treatment for fever
Signed autograph letter.
The manuscript is to be found in London, Royal Society, MS 2063, Early Letters L.4.12
A second, signed autograph manuscript is to be found in The Hague, Nationaal Archief, Archief Anthonie Heinsius, toeg.nr. 3.01.19, inv.nr. 1204; 15 folio pages, with 3 figures in red chalk (ms. H). This letter was sent to Heinsius under the cover of Letter 271 of August 10, 1707.
12 quarto pages (ms. L).
Leeuwenhoek did not include the letters from 1702-04-28 (AB 237) through 1712-06-10 (AB 294) among his self-published and thus self-numbered letters. Those with scientific observations were all addressed to members of the Royal Society and almost all of them were excerpted in Philosophical Transactions.