Christiaan Huygens wrote Letter L-208 to Leeuwenhoek about liquids in glass balls and Iceland crystal

March 6, 1690

No manuscript is known.

Huygens sent Leeuwenhoek a copy of his recently published books, Traite de la lumiere, and a small piece of what he called Iceland crystal and we now call Iceland spar (crystallized calcium carbonate). The crystal part of the name noted its transparency, which affected light passing through it in ways Huygens was interested in. In this cover letter, he asked whether Leeuwenhoek could extract any water from it.

He also wrote about Leeuwenhoek’s experiments with a hollow glass ball and how liquids behave in it. His explanation was accompanied by a rough sketch (right).

This letter is known only by the summary in Oeuvres completes, to be found in the Huygens Collection, University Library, Leiden.

Traité de la Lumière: Où Sont Expliquées les Causes de ce qui Luy Arrive Dans la Reflexion & Dans la Refraction (Treatise on light: In which are explained the causes of that which occurs in reflection & refraction) was published in 1690 by Pierre [Pieter] van der Aa in Leiden. It introduced Huygen’s wave theory of light in opposition to both Descartes’s Dioptique and Newton’s particle theory of light.

Iceland crystal, now known as Iceland spar, is a transparent calcite used by Huygens to study the polarization of light.

For more about Leeuwenhoek’s experiments with a hollow glass ball, see Letter L-294 of 10 July 1696 to Nicolaas Witsen. In it, L. recalled a visit from Huygens:

A few years ago, when Mr. Chr. Huygens of Zuylighem did me the honour of visiting me, our conversation turned to the motion of the Earth, on which occasion I produced a flask fitted as shown in the accompanying drawing. And when I set the flask in motion, the said gentleman took such pleasure in it that I felt obliged to present him with such a flask, with which he was quite pleased.

For a complete list of known visitors to L.’s house, see Appendix 16, Collected Letters, vol. 20.


Oeuvres complètes vol. IX. Correspondence 1685-1690, p. 390, No 2571.

Sendt een Exemplaer van mijn boeck. Heb gedacht op sijn Experiment met den glasen bol in plaets van mijn vlacke cylindrische vat. Waerom dat sijn bol niet soo bequaem daertoe is. te weten om dat het lack in 't eerst van 't draeijen, moeijte heeft om naer AB op te klimmen. En daer nae als het glas vast gehouden werdt, soo is het lack genegen om nae C te trecken, waer door van het glas af gaet in E en F komt, en eerst weer op den grond moet sacken eer het nae 't midden D sich begeeft. daer om de vlacke bodem beter is. 't waer goet oock gewicht aen 't vat te voegen om in 't eerst beter te draeijen. Men kan een platte open doos van blick laeten maecken en met een glas toe decken. Ick send een stuckje Yslands Cristal om te sien of daar water uyt te halen is door sijn distillatie. sal bij gelegentheydt grooter senden.