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|Spaltenumbruch|
Germination, chemical experimentsrespecting. The late diſcoveries in chemiſtry,have thrown much light on this ſubject. In1793, M. Humboldt diſcovered, that ſimple me-tallic ſubſtances are not favourable to the germina-tion of plants, but that metallic oxides favour it inproportion to their degree of oxidation. Thisled him to ſearch for a ſubſtance with which oxy-gen might be ſo weakly combined as to be eaſilyſeparated, and he tried oxygenated muriatic acidgas mixed with water. Creſſes (See Lepidium,
N° 2.) in this acid ſhewed germs at the end of 6hours, and in common water at the end of 32hours. The action of the acid on the vegetableſibres was announced by a great number of air-bubbles covering the ſeeds, which did not takeplace with water till the end of from 30 to 45minutes. Theſe experiments, publiſhed in Hum-boldt’s Flora Subterranea Fribergenſis, and in his
Aphoriſms on the Chemical Phyſiology of Plants, have
|Spaltenumbruch| been repeated by Meſſrs Uſlar, Plenck, Vildenow,and others. See Dictionaire de Phyſique, par Geh-ler. They were made at a temperature of from12 to 15 of Reaumur. In 1796, Humboldt madeſome new experiments, and found that, by join-ing caloric to oxygen, vegetation was ſtill more ac-celerated. He threw equal quantities of the ſeedsof garden creſſes into pure water and oxygenatedmuriatic acid, at a temperature of 58° F. Creſ-ſes germinated in the acid in 3 hours, but in thewater not till the end of 26 hours. In the muri-atic, nitric, or ſulphuric acid, there was no germat all; though, according to the experiments ofM. Candolle, the nitric acid accelerates germina-tion alſo, when greatly diluted with water. Prof.
Pohl at Dreſden cauſed the ſeed of a new ſpeciesof Euphorbia to germinate in oxygenated mu-riatic acid, though taken from Bocconi’s collec-tion of dried plants, 110 or 120 years old. Jac-quin and
Van der Schott at Vienna threw intooxygenated muriatic acid all the old ſeeds, whichhad been kept 20 or 30 years at the botanicalgarden, every attempt to produce vegetation inwhich had proved fruitleſs , and the greater partof them, even the hardeſt ſeeds, germinated. A-mong theſe were the yellow bonduc, or nickartree, (See Guilandina, N° 1.) the pigeon pea,(See Cytisus, N° 2.) the Dodonæa Anguſtifolia,
the climbing mimoſa, (See Mimosa, N° 19.)and ſome new ſpecies of the
Homæa. There arenow ſhewn at Vienna very valuable plants, whichare entirely raiſed by the oxygenated muriaticacid, and are from 5 to 8 inches high. Hum-boldt made the cluſia roſea to germinate, the ſeedsof which had been brought from the Bahamaiſlands by Booſe, and had reſiſted every previouseffort to make them vegetate. For this purposehe uſed a new proceſs, which will be eaſier forgardeners who cannot procure the oxygenatedmuriatic acid. He formed a paſte by mixing theſeeds with the black oxide of manganeſe, and thenpoured over it the muriatic acid diluted with wa-ter, in the proportion of half a cubic inch of theacid to 3 of water. The veſſel containing thismixture muſt be covered, but not ſhut cloſe, leſtit ſhould burſt. At the temperature of 95°, themuriatic acid becomes ſtrongly oxydated; theoxygenated muriatic gas which is diſengaged paſ-ſes through the ſeeds; and during this paſſage theirritation of the vegetable fibres takes place. Phi-loſ. Mag.
