■Et&opfan Sugar. — StruSfure of Vegetables. 31I 



experiment for azotic gas, there is alfo a prodiiftlon of car- 

 bonic acid gas; but that the atmofphere of the plant dc- 

 creafes, and that the oxygen gas is abforbed. He made ft;- 

 veral experiments to difcover what takes place in thefe opera- 

 tions. The following are his conclufions : 



J. The atmofpheric oxygen gas is not abforbed by the feed 

 in the aO: of germination, as fcems hitherto to have been ad- 

 mitted, but is employed merely to form carbonic acid gas 

 with the carbon of the {Qcd. 



2. The feed in germination does not, by the contaftof the 

 atmofpheric air, form carbonic acid gas from its own fub- 

 ftancc, but only furmflies one of the conftituent parts of that 

 gas, fiz. carbon. 



3. It furniflies the oxygen and carbon from its own fub- 

 ftance in the carbonic acid gas, which it produces when it 

 is in contact only with water and pure azotic gas. 



Though the action which the vegetation of plants exercifes 

 on atmofpheric air has been examined by a great number of 

 philofophers, much on this head is ftill wanting. Spallan- 

 zani, who has been lately fnatched from the fciences, has 

 alfo examined this fubjeit. He concludes from his experi- 

 ments : 



1. That the leaves and tops of vegetables, when the rays 

 of the fun dart upon them, increafe the proportion of the 

 oxygen gas of the atmofpheric air. 



2. That this augmentation is not fo confidcrable as has 

 been believed. 



3. That the fame parts of vegetables diminifh the oxygen 

 ffas during the night, and cloudy days, by transforming it 

 conlinuallv though flowly into carbonic acid. 



4. That the flowers, whether in the fun or fliade, have more 

 power to diminifli the quantity of vital air or oxygen gas. 



5. That fruit have the fame effefts in this refpeCl as flovvcrs. 

 Delaville has examined feveral plants which afforded him 



fugar; fuch as the mallow, digitalis purpurea, cabbage, the leaves 

 of the artichoke. The beet-root gave alfo a large quantity. 



Desfontaincs has publifhed his excellent memoir on the 

 ftru6lurc of the monocotyledons, or plants with one feminal 

 Ifaf, £ucb as palms, afparagus, ruflies, 8cc. He has fliowa 



tlut 



