Henry Oldenburg wrote Letter L-010 to Leeuwenhoek requesting that he examine saliva, chyle, and sweat

May 4, 1674

When Oldenburg wrote this letter, it was 24 April 1674 in London. It is known only by reference in other letters

Leeuwenhoek mentioned this letter in Letter L-011 of 1674-06-01. In Letter L-012 of 1674-07-06, he examined saliva, chyle, sweat, etc., as Oldenburg had requested.

Leeuwenhoek again mentioned it in his Letter L-060 of 1677-11-01 to William Brouncker. We have only the Latin translation of that letter, in which Leeuwenhoek reports his observations of human sperm, as Oldenburg had requested.

The letter was calendared in The Correspondence of Henry Oldenburg vol. X, p. 568.

This letter is Oldenburg’s first to L., after L. had already sent five letters to him. His next letter is Letter L-013 of 30 August 1674, in this volume. Between them, L. sent two letters. In Letter L-011 of 1 June 1674, L. examines the structure and nature of blood, as Boyle requested. In Letter L-012 of 6 July 1674, L. examines saliva, chyle, sweat, etc., as Oldenburg requested.

In total, the correspondence between Oldenburg and L. over the four years up to Oldenburg’s death in September 1677 includes 45 letters, 18 from Oldenburg to L. and 27 to Oldenburg from L., 11 of which Oldenburg published in 12 articles in volumes 8 through 12 of Philosophical Transactions.

For Henry Oldenburg (1615?-1677), one of the founders of the Royal Society and the owner and editor of its journal Philosophical Transactions, see a short biography published three months after his death in Birch, The History of the Royal Society of London, vol. III, pp. 353-356.


The manuscript is missing; this letter was never printed.

Letter L-011 of 1 June 1674 to Henry Oldenburg:

Yours of the 24th of April, as also the two Philosophical Transactions, reached me in safety and were very welcome to me. I am very much obliged to you and understand from your letter with great contentment, that my inconsiderable microscopical communications have not been unacceptable to the Royal Society, and that, among others, Mr. Boyle advises me to continue them and especially to pay attention to the red, florid colour that blood acquires as soon as it is drawn from the veins and exposed to the air, and also to the blood under the surface, as being distinct from the other blood in colour.

Letter L-060 of November 1677 to William Brouncker:

I find that I was asked on April 24th 1674 by my London correspondent to examine also saliva, chyle, sweat, etc.