Experiments and observations on the vegetation of plants : which shew that the common opinion of the amelioration of the atmosphere by vegetation in solar light, is ill founded / by James Woodhouse.

  • Woodhouse, James, 1770-1809.
Date:
[1802?]
Catalogue details

Licence: Public Domain Mark

Credit: Experiments and observations on the vegetation of plants : which shew that the common opinion of the amelioration of the atmosphere by vegetation in solar light, is ill founded / by James Woodhouse. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    plants, and to the temperature to which they are fubje&ed, it appears more rational to afcribe the generation of it to the coal I of the decayed parts uniting with the oxigen of the air in which they are placed. aves expofed To determine whether plants would abforb or devour azotic o funfhine in a . , , ,. >.,. . . , .,, ,,. , , nixtureof at- gas> e'g»t ounce meaiures or this air were mixed with tnirty- bofpherk air two ounce meafures of atmofpheric air, fo that its purity was uced^no'effeft. recmced from 100 to 91. A handful of the leaves of euphorbia picla and coryllus avellana were feparately confined in forty ounce meafures of this air, and expofed to the influence of a (bright folar light five hours. No carbonic acid gas was gener- ated, and the purity of the air was exa£tly the fame as when firfr. tried. No decayed portion could be obferved upon thefe leaves, .eaves do not As it is acknowledged that the leaves, ftems, and roots of of hereby de- P^an^s* Separate the oxigen from carbonic acid, it may be faid, >mpofmg its that the oxigenous portion of atmofpheric air is fupplied by the irbonic gas; decompofition of this gas, as it is always found in the atmo- jantity of this fphere, and often in water in which vegetables grow, is is very mi- ^he quantity of carbonic acid gas in atmofpheric air, is reckoned to be about one part in an hundred. It mutt, how- ever, vary in different places. We would expeft to find the mod of it in cities, where it is formed by combuftion, refpira- tion, fermentation, and putrefaction. If one meafure of the air of any large city is thrown up over lime-water in an eudio- meter, no milky appearance will be produced, fo that the quan- tity of carbonic acid in this air muft be extremely fmall. As this gas is alfo feized upon by alkalis, earths, and metals, and abforbed by water, the quantity floating in the atmofphere may be lefs than one part in ten thoufand. id plants dete- When we confider likewife, that the oxigen is never fepa- orate the air rate(j from the carbonic acid by leaves, but when they are ex- pofed, in contact with it, to the light of the fun; and that every perforation made in the living leaf, however minute, by an in- fect, caufes the part to decay, and abforb oxigen by day and by night; and that, in the autumn in fome countries, all leaves fall on the ground, ferment or putrify, and thus diminifli the purity of common air; and that the petals and fruit of vege- tables have the fame effedt, we muft pronounce, that the oxi- genous portion of atmofpheric air cannot be fupplied by vege- tation. Dr.