Henry Oldenburg wrote Letter L-017 to Leeuwenhoek encouraging him and asking about the kind of salt he was observing

November 5, 1674

Oldenburg wrote this letter on 26 October 1674 in London. It is known only by reference in other letters.

He acknowledged receiving Leeuwenhoek's recent letters, relayed greetings from Robert Boyle, and again encouraged Leeuwenhoek to continue sending his observations. He also asked for clarification about what L. meant by “musk” and about what kind of salt Leeuwenhoek was observing.

Leeuwenhoek replied to this letter on Letter L-018 of 1674-12-04.

This letter is calendared as Letter 2564 in Hall and Hall, The Correspondence of Henry Oldenburg, vol. XI, May 1674–September 1675, p. 116.

Oldenburg’s previous letter to Leeuwenhoek is Letter L-013 of 30 August 1674. Leeuwenhoek replied with Letter L-014 of 7 September 1674, Letter L-015 of the same date, and Letter L-016 of 19 October 1674.


The manuscript is missing; this letter was never published.

Letter L-018 of 4 December 1674 to Henry Oldenburg

I see my two last letters reached you, and that my trifling observations contained in them were welcome to you. I kindly thank you for your obliging letter of 26 October last. Please remember me to Mr. Boyle and thank him for not forgetting me.

The salt mentioned in my letter of September 7th is common salt and I never thought at the time of any other salt. You say there are two lines in the same letter that require being expressed more clearly.

The musk-coloured matter which I saw in the eye, I have found to be musk-coloured globules. ... You express a wish that I shall examine various sorts of wine with my microscope. I have often intended to do so, but the moist and vaporous air does not permit this at present.

Letter L-026 of 14 August 1675 to Henry Oldenburg

You had the kindness in your letter of October 26th 1674 to ask me to examine the sap of plants. I have examined several saps and observed in them various figures, of which I have made rough drafts on paper. It would entail too much writing if I were to describe all these saps and besides, instead of interesting the virtuosi, I am afraid they would be bored. ...

At your request I have examined several kinds of wine, in which I generally found little figures of a neatness beyond expression. But their forms, and the reason why some wine is sour and some has a pleasant taste I shall not enter upon here, for fear of tackling too many things at a time.