Volume 11

Alle de brieven van Antoni van Leeuwenhoek / uitgegeven, geïllustreerd en van aanteekeningen voorzien door een Commissie van Nederlandsche geleerden.

  • Antonie van Leeuwenhoek
Date:
1939-
Catalogue details

Licence: Public Domain Mark

Credit: Alle de brieven van Antoni van Leeuwenhoek / uitgegeven, geïllustreerd en van aanteekeningen voorzien door een Commissie van Nederlandsche geleerden. Source: Wellcome Collection.

    33/406 (page 17)
    But when I again lit a candle and proceeded with it as described above, all the said Salt figures again crystallized, even if I repeated the said procedure three of four times, during which the softness of the Salt particles appeared even more clearly to me. After this I had a look at the slide on which the layer of the fluid substan¬ ce was so thin that it had only flown over it, where there was a multitude of mil¬ lions of little particles, which could not be distinguished because of their small¬ ness, and although this slide had been (in the winter) for more than eight days in the air in my study, yet all the Salt particles were enveloped with a fluid substance; and when I held this slide before my eyes and at a distance before the candle, I saw that in a short time the fluid substance evaporated and that practically all the said little particles were Salt particles, for they became elongated on the sides and crystallized in crosswise particles, which were somewhat like quadrilateral figures. Others had at one end a very small square or quadrilateral figure10). From this sight 1 concluded that the real form of the greater part of the Salt particles, how¬ ever small they might be, was a square, and that the irregularity of crystallization was caused only by the small amount of fluid in which this crystallization took place11). Further I took the substance I removed from my Ears with an Ear-pick, which was a very small amount because I had cleaned my Ears two days ago. I placed this substance also in a new glass [tube] and, having poured some rain-water on it, from said substance I saw a large number of very small air bubbles emerging, which at first were as small as a grain of common Sand12) appears to the naked eye, and I saw that these small air bubbles very slowly increased in size until many of them appeared as large as peas when viewed through the magnifying glass13). On several little particles of substance these air bubbles were so numerous that the substance from the Ear, which through its heaviness first sank to the bot- l0) Here again L. probably saw urate crystals. [Han.] ) About the crystallization of salt L. wrote in Letter 141 [86] of 10 April 1695, Collected Letters, vol. 10, pp. 173-175. For the growth of crystals of common salt and substances originating, inter alia, from all sorts of herbs see Letter 16 [10] of 11 February 1675, idem, vol. 1, pp. 233-249 and note 25 to Letter 18 [12] of 14 August 1675, ibid., p. 311. L. goes further into the shape of the crystals of all sorts of substances and the relation with the taste which they cause in Letter 83 [44] of 23 January 1685, idem, vol. 5, pp. 69-137. For the backgrounds of L.'s theories about the structure of crystals see Hooykaas, „Kristalmoleculen”, pp. 441 -442. 12) Agrainofcommon Sandis400g. u) In ear wax indeed large air bubbles enveloped with an oily membrane are often visible, which sometimes unite or disappear. [Han.] For an earlier investigation about ear wax, see Letter 134 [80] of 2 March 1694, Collected Letters, vol. 10, pp. 7-13. Air bubbles from ear-wax.