An essay on dew, and several appearances connected with it / by William Charles Wells, M.D. F.R.S.

  • William Charles Wells
Date:
1814
Catalogue details

Licence: Public Domain Mark

Credit: An essay on dew, and several appearances connected with it / by William Charles Wells, M.D. F.R.S. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    I saw, for example, platina one night distinctly dewed, while gold, silver, copper, and tin, though similarly situated, were entirely dry; and I have also several times seen these four metals free from dew, while iron, steel, zinc, and lead were covered with it. I once supposed, in consequence of the diffi- culty with which metals are dewed, that they might in all circumstances resist, in a greater degree than other bodies, the condensation of watery vapour upon their surface, and I after- wards found, that Le Roi* asserts this to be the case. But, having exposed at the same time, to the steam of warm water, pieces of glass and of metal, I did not see that moisture formed in the least more readily, upon the former than upon the latter. I have since learned, that Saussuref once entertained a similar suspicion, which was also proved by an experiment to be groundless. All my experiments, hitherto spoken of, were made in the country. But Le Roi having said, that dew is never deposited by the air of cities, I determined to ascertain, if his assertion was just. With this view, I frequently exposed, at night, 10 grains of wool upon a slight wooden frame, placed in such a manner, between two ridges of 1 !■'* * Mem. de l'Acad. Fran. 1751. f Hygronometrie, p. 329.
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