310 On the Effeils of Oxygen 



of 32 hours. The aftion of the firfk fluid on the vegetable 

 fibres js announced by an enormous quantity of air bubbles 

 which cover the feeds, a phenomenon not exhibited by 

 water till at the end of from 30 to 45 minutes. Thefe 

 experiments announced in Humboldt's Flora Subterranea 

 Fribergerjis, and in his Aphorifms on the chemical phyfiology 

 of Plants, have been repeated by others *. They were made 

 at a temperature of from 12 to 15 Reaumur. In the fum- 

 mer of 1796, Humboldt began a new feries of experiments, 

 and found that by joining the ftimulus of caloric to that of 

 oxygen he was enabled Mill more to accelerate the progrefs 

 of vegetation. He took the feeds of garden crefles (lepidium 

 fattvum), peas (pifum fat'ivum), French beans (phafeolus vul- 

 garis}) garden lettuce [lacluca fativa)) mignonette {refeda 

 odorata); equal quantities of which were thrown into pure 

 water and the oxygenated muriatic acid at a temperature of 

 88° F. Creffes exhibited germs in three hours in the oxygen- 

 ated muriatic acid, while none .. :: feen in water till the 

 end of 26 hours. In the muriatic, nitric f or fulphuric 

 acid, pure or mixed with water, there was no germ at all : 

 the oxygen feemed there to be too intimately united with 

 bafes of azot or fulphur, to be difengaged by the affinities 

 prefented by the fibres of the vegetable. The author an- 

 nounces that his difcoveries may one day be of great benefit 

 in the cultivation of plants. His experiments have been 

 repeated with great induftry and zeal by feveral diftinguifhed 



* See Uflar's Fragments of Phythology, Plenck's Phyfiology, VilJde- 

 now's Dendrology, and Diilionnaire de Pbyfiqur. par Gehler. 



f The nitric acid, however, diluted with a great deal cf water, accele- 

 rates germin;.t ; on alfo, according to the experiments of Candolle, a young 

 naturalft, who has applied with great fbecefs to vegetable phyfiology. 

 This phenomenon is the more intertfting, as chemiftry affords other ana- 

 logics of the oxygenated muriatic acid and the nitric acid. Profeffor 

 Pfafs, at Kiel, by purfuing Humboldt's experiments, lias found that frogs 

 fuffocated in oxyg< nated muriatic acid gas increafe in irritability, while thofe 

 which perish in carbonic acid gas are lefs fenlible of Galvanifm. 



philo* 



