Essays on the floating-matter of the air in relation to putrefaction and infection / by John Tyndall.

  • Tyndall, John, 1820-1893.
Date:
1881
Catalogue details

Licence: Public Domain Mark

Credit: Essays on the floating-matter of the air in relation to putrefaction and infection / by John Tyndall. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    25/366 (page 21)
    ON DUST AND DISEASE. I. Experiments on Dusty Air. Solar light, in passing through a dark room, reveals its track by illuminating the dust floating in the air. ‘ The sun,’ says Daniel Culverwell, ‘ discovers atomes, though they be invisible by candle-light, and makes them dance naked in his beams.’ In my researches on the decomposition of vapours by light, I was compelled to remove these ‘ atomes ’ and this dust. It was essential that the space con- taining the vapours should embrace no visible thing— that no substance capable of scattering light in the slightest sensible degree shoidd, at the outset of an experiment, be found in the wide ‘ experimental tube ’ in which the vapour was enclosed. For a long time I was troubled by the appearance there of floating matter, which, though invisible in diffuse daylight, was at once revealed by a powerfully condensed beam. Two U-tubes were placed in suc- cession in the path of the air, before it entered the liquid whose vapour was to be carried into the experi- mental tube. One of the U-tubes contained fragments of marble wetted with a strong solution of caustic potash ; B