QS *?UXRlTroN OF VSGETABtEb. 



which appeared evidently to have been formed at the ex- 

 pense of water, and probably of li<^ht*, 

 Arpuments Geoloujlcal facts too seem to shake that theory, which as- 



froin geology cribes the carbon found in vegetables to the small quantity 



thaithfcavbon of carbonic acid contained in the atmosphere. How indeed 



o!^ jlant>. does , . . 



Ti jt come from can so small a portion of this acid, scarcely amounting to a 

 • atmos- ^pj^ thonsandth part of the air, explain the formation of those 

 vast mines of pitcoal, which still retains the marks of those 

 organized substances whence it originated, and the organic 

 origin of which is sufficiently announced by its composition 

 of carbon, hidrogen, oxigen, and azote ? But without appeal- 

 ing to these ancient productions of the vegetable kingdom, 

 burled in the earth in such abundance, we need only cast an 

 eye on its surface, to satisfy ourselves that nature must have 

 taken other steps to produce carbon. 



Charcoal pro- On the other hand, if, in the silent progress of vegetation, 



duced from ^|^g elements of water concur with the solar light to produce 

 water, and . , • • i 



therefore con- charcoal by mtmiate combmations unknown to us, charcoal 



fains hidiogen. oug]^^ to contain hidrogen likewise; and this is confirmed by 

 experience. 



Proofs of this. If charcoal strongly calcined be urged in the fire with a 

 substance that has an affinity for hidrogen, the charcoal is 

 partly decomposed, and hidrogurettcd products are obtained. 



Light neces- 



* To satisfy myself, that plants can appropriate to themselves the ele- 

 sary to the pro- nients of water, so as to constitute their different materials, only by their 

 duciion of car- own organic action combined with that of light, I caused a given quan- 

 bon in plants, ^ity of seed to grow in complete darkness, and at the common tempera- 

 ture of the air. They shot out long white filaments, at the extremity of 

 v/hich were the two seminal leaves; but nothing more appeared. After 

 desiccation these plants weighed less than the seeds whence they sprung : 

 which appeared to be owing to their having lost carbon in this languisli- 

 ing state, instead of acquiring it, 

 A re tl ♦ "t ^"^ ^^^ mode of action of light on vegetables remains yet to be known, 

 combines with It appears however, that it enters into combination with them, and that 

 them. to this combination is owing the green colour of their leaves, and the va- 



riety of hues admired in their flowers. Yet Mr. Humboldt has found 

 green plants growing in deep and dark mines, the atmosphere of which 

 contained a great deal of hidrogen. Does not this fact indicate some- 

 Perhap? ana- thing common between hidrogen and light, particularly when we ob- 

 logous with hi* serve, that these two fluids, the lightest in nature, seem likewise to pro- 

 rogen. ^^^^ analogous effects on some metallic oxides and salt ? 



Mr. 



