152 ON THE VEGETATION OF PLANTS. 



II. Of the Effecls produced by the Growth of Plants in atmofphe- 

 rical Air. 



Growth of plants On the 27 th of May, twelve plants ofperficafia polygonum, 



inatraof. air. . . , ,., *\ . *".. F <: i • i / 



two inches high, growing in earth, were confined in a glals 



veflel in fifty-two ounce mcafures of atmofpherical air, of the 

 purity of 100, and often expofed to the influence of folar light. 

 On the 4th of June, they had increafed about two inches in 

 height. The air being examined at this time, was found to 

 contain j^jj parts of carbonic acid gas, and to be reduced in 

 purity to 80. Several young plants of rhaphanus fativus, la- 

 tura ftramonium, phytolacca decandra, zea maiz, phafeolus 

 jativus, fidum telephium, amaranthus hyboidus, cucurbita ci- 

 trullus, firymbrium, and lactuca fativa, were alfo feparately 

 confined in from forty to eighty ounce meafures of atmofpheri- 

 cal air, which was examined at various times, from one hour 

 They produced to thirty days, after the plants had been placed in it. Carbo- 

 carbon:c acid n j c ac j c j was pr enera Ily formed, and whenever this circum- 



gas, and dirni- " b . r ' . ,- • •„ i 



nifhed the purity fiance happened, the purity of the air was dimimflied. 

 of the air. Many of the fame kind of vegetables were alfo confined in 



in^xigendimi- f° rtv ounce meafures of oxigenous gas, which had been well 

 nifhiti purity by warned in lime water, and the purity of the air was very gene- 

 car omc aci . ra jj^ ] e flr- enec ^ ^ xe( j a j r being generated. They turned of a 

 white or yellow colour, and foon died, after being placed in at- 

 mofpherical air. 

 In confined The fame effects are produced by the growth of plants as by 



plants the de- t ne germination of feeds in common air, and by the fame caufes. 

 ford carbon and If the leaves are confined a confiderable time, part of them de- 

 form acid, which cay, and the coal of the dead portion, uniting with the oxigen 

 Lcompofes!/ 11 °f the atmofpheric air, generates carbonic acid. This acid is 

 decompofed by the living leaf. Its coal is abftra&ed, while its 

 oxigen is left in the form of pure air. 

 But when the When the oxigen unites to the coal of the animal or vegc- 



formation is ta b] e matter of the foil in which the plants vegetate, or to the 

 cjuiclcer than the „ r to . 



decompofiti on, coa l of the decayed parts of the leaves, and makes fixed air 



the plant dies, quicker than the living parts can decompofe it, the plants will 



fpeedily die. 

 When the foil When a plant in ] crfecl health, growing in a foil which con- 



contains but tains tittle vegetable or animal matter, is confined in atmOfphe- 

 izcVi^rnainT" r ' ca ^ a ' r * '*■ W *W nve a l° n g time, without producing any change 

 the included in it. Many of the vegetables which were the fubje&s of thefe 



P lan !7 ,ilivc experiments, 



much longer. r 



