July 1676


Leeuwenhoek wrote two letters dated July 28. The first (AB 24) was addressed to Henry Oldenburg and is lost. Perhaps is was a cover letter or enclosure for the second (AB 25). This letter was addressed directly to Robert Boyle about the effects of air on the chemical combination of ammonia and copper. Leeuwenhoek was responding to an article that Boyle had published in 1675 in volume 10 of Philosophical Transactions.

His back-and-forth with Grew had been through Oldenburg. But Leeuwenhoek seems to have gained the confidence to initiate a discussion with another famous foreign scientist. He had finished answering the questions that Boyle's article had raised, and he wanted to tell Boyle about it.

With the help of an English and Dutch dictionary (since I do not know the English language) I understood from Transaction Nr. 120 that you had put some copper-filings in spirit of salts etc. and since I had in my study spirits of sal ammoniac which served me for several observations I was eager to repeat your observations.

He may have used Henry Hexham's dictionary, the second edition of which had just been published the previous year.

What was going on in London in response to the increasingly contentious and bold Leeuwenhoek? Birch's History is silent. Were Leeuwenhoek's letters read or discussed in the coffee houses? We don't know whether he was being ignored or rejected. We know only that few letters were published, and that was Oldenburg's decision. Grew's extraordinary response indicates a willingness to engage Leeuwenhoek, but not about his "small living creatures."

We also know from Leeuwenhoek's occasional comments that Oldenburg, at least, was pushing back and Leeuwenhoek was searching for reasons why he was not being published.

In any case, whether or not due to the reactions in London, Leeuwenhoek was continuing his observations of the little creatures in a more organized, systematic manner. While his publishing career had hit a dry spell, Leeuwenhoek continued conducting an extended series of observations and experiments with his animalcules.

Perhaps someone else would have given up or stopped sending letters if they weren't going to get published. Instead, the ever-curious Leeuwenhoek came on stronger.


Experiments beginning in July
Infusion preparation start end duration observation
Well       July 24
Nutmeg pieces of beaten nutmegs in 2? oz well water with no living creatures, save a few extraordinay small July 13 Sept 7 8 weeks 128 - 145
Sea   July 27 August 8 12 days 25 - 30