COLLEGE LIFE. Ill 



I go moss hunting, as Forster calls it. Werner shows me much 

 kindness, and for the cordial reception I have met with at the 

 house of Charpentier I am indebted to you, my dear friend.' 



Under Werner and Charpentier, with both of whom he was 

 admitted to familiar intercourse, Humboldt devoted himself 

 with true enthusiasm to the study of the art of mining, not 

 only as a science but also in its practical details. His 6 Flora 

 subterranea Fribergensis ' testifies to the wide circuit of his 

 wanderings in the extensive labyrinths of the mines around 

 Freiberg expeditions which he took according to the plan laid 

 down by Werner, in company with Freiesleben, impelled by 

 the excitement so often kindled in young and ardent natures 

 by the dangers of subterranean explorations. 



Various other studies of a different nature also strongly ex- 

 cited his interest at this time, and were carried on during his 

 leisure hours. As no official instruction was then given in 

 chemistry, he devoted himself to the study of the works of 

 the French chemists, Gruyton de Moreau, Fourcroy, Lavoisier, 

 and Berthollet a pursuit in which he enjoyed the sympathetic 

 companionship of Franz Baader of Munich, who had already been 

 three years in Freiberg, and had made himself a name by his 

 treatise on the nature of heat, and reviews of scientific works. 

 It was while engaged in the study of fossils, during these 

 wanderings in the vast subterranean passages, that he conceived 

 the happy idea of turning his attention to the vegetation of 

 that lower world from which the light of day is ever excluded. 

 His ' Experiments and Observations on the Green Colour of 

 Subterraneous Vegetation,' the result of his researches in his 

 4 small subterraneous garden/ which could not be visited by a 

 single ray of sunshine, and could at most be illuminated by 

 the meagre, unproductive light of a miner's lantern, is closely 

 allied to the investigations of Bonnet, Priestley, Ingenhouss, 

 and Sennebier upon the influence of sunlight on vegetable 

 organisms, and was a preparation for his comprehensive work 

 on the physiology of plants, c Flora subterranea Fribergensis/ 

 The phenomenon that vegetation, even when wholly excluded 

 from light, was yet tinged with various shades of green, re- 

 garded at that time as a very extraordinary fact, was explained 

 by Humboldt to arise from the disengagement of oxygen, in 



