Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 1 - By Alexander Von Humboldt And Aime Bonpland.
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They Were A Mixture Of Azotic Gas And
Carbonic Acid.
Nitrous gas scarcely indicated the presence of
oxygen.* (* In a hundred parts there were eighty-four of nitrogen,
fifteen
Of carbonic acid gas that the water had not absorbed, and
one of oxygen.) Lastly, I set the wood and the roots of the
mangrove thoroughly wetted, to act on a given volume of atmospheric
air in a phial with a ground-glass stopple. The whole of the oxygen
disappeared; and, far from being superseded by carbonic acid,
lime-water indicated only 0.02. There was even a diminution of the
volume of air, more than correspondent with the oxygen absorbed.
These slight experiments led me to conclude that it is the
moistened bark and wood which act upon the atmosphere in the
forests of mangrove-trees, and not the water strongly tinged with
yellow, forming a distinct band along the coasts. In pursuing the
different stages of the decomposition of the ligneous matter, I
observed no appearance of a disengagement of sulphuretted hydrogen,
to which many travellers attribute the smell perceived amidst
mangroves. The decomposition of the earthy and alkaline sulphates,
and their transition to the state of sulphurets, may no doubt
favour this disengagement in many littoral and marine plants; for
instance, in the fuci: but I am rather inclined to think that the
rhizophora, the avicennia, and the conocarpus, augment the
insalubrity of the air by the animal matter which they contain
conjointly with tannin. These shrubs belong to the three natural
families of the Lorantheae, the Combretaceae, and the Pyrenaceae,
in which the astringent principle abounds; this principle
accompanies gelatin, even in the bark of beech, alder, and
nut-trees.
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