Angelus van Wikhuysen wrote Letter L-456 of 15 July 1707 in defense of using cinchona bark as medicine

July 15, 1707

This letter is known only by reference in another letter.

In this letter, Van Wijkhuysen wrote in response to Leeuwenhoek’s study of China Chinae (quinine) that in his experience, contrary to the experience of others, its use as medicine does not cause greater problems than the problem it is used to treat.

Angelus van Wijkhuysen, a doctor from Zeeland, visited Leeuwenhoek frequently; presumably, most of their correspondence is lost. Leeuwenhoek's only known letter to van Wijkhuysen is Letter L-449 of 1707. The previous letter from Van Wijkhuysen to Leeuwenhoek is Letter L-259 of sometime before July 1695.

Leeuwenhoek told the Royal Society about Van Wijkhuysen’s use of China Chinae (quinine) in detail at the beginning of Letter L-457 of 25 July 1707

I have been acquainted for many years with Mr. Angolus van Wikhuijsen, doctor of medicine, living in Middelburg, in Zeeland, whom I esteem very much, because he has frequently said to me (as did also several other learned gentlemen) that he knew very little of medical science, and that usually he produced good results with simple things.

When the said gentleman visited me last year, as well as this summer, as he comes over here every year to settle his affairs, our conversation touched again on the rind or bark of the tree that is called China Chinae, which he used with great success in the case of persistent fever. ...

Now that gentleman again frankly tells me how he used the China Chinae, and that he infallibly cured therewith all intermittent fever adding that he would be very pleased if I made this public.

He causes the China Chinae to be pounded to a fine powder, and when it has been passed through the finest sieve, he takes two drachms and puts them in about one fourth of a pint of French wine and administers the said powder mixed with wine. Or else he takes about one ounce of the said fine powder, sixteen of which ounces make one pound, and puts it in a glass bottle in which there are about one and a half pints of French wine, and thus lets it stand until it is used.

His instruction is that one must shake the bottle vigorously one hour before the fever rises, in order that the powder on the bottom may be thoroughly mixed with the wine, and thus drinks one fourth of the mixed wine (for the said wine in the bottle is intended for four doses) against the future onset of the fever and, if it should return uses as much the second time; and this procedure has not miscarried once in a hundred cases.


Letter 270 L-457 of 25 July 1707 to the Royal Society

When I had committed this to paper thus far, I wrote as follows to Mr. van Wikhuijsen.

“I remember that some years ago I learned about the China Chinae, but that it should only be used with the greatest caution, because now and then it harmed the body in such a way that, although the fever did not arise, the trouble that followed was a greater evil than the fever itself. Since Your Honour has had much experience with China Chinae, you will no doubt know with sufficient certainty whether the said medicament entails any illness, which I shall be pleased to learn.”

To this the said gentleman from Middelburg replied in his letter of the 15th of July, among other things, as follows.

“I know indeed that many people are of this opinion, but I do not know on what ground this is based. I can state that I have never found this to happen from experience, and I think that I have used it so often as few others will be found [to have done].”