ON THE VEGETATION OF PLANTS. 153 



experiments, did not affecl the air in five days : fome diminifh- 

 ed its purity in three hours; and others altered it in a mod flow 

 and gradual manner, caufing little change in it in twenty 

 days. 



III. Of the E feels produced by the Leaves of Plants in atmofphe- Leaves expofed 



rical Air impregnated xvith Carbonic Acid Gas, and expofed to ^xtmz^i at> * 



the Light of the Sun. mofphericand 



carbonic acid gas. 

 A handfull of the leaves of mimofa virgata, euphorbia picla, 



digitalis purpurea, franklinia altamaha, afparagus officinalis, 

 coryllus avellana, rhus glabrum, ariftotochia fiphoe, and peri- 

 ploca graeca, were feparately expofed feven hours to the light 

 of the fun, in thirty-fix ounce meafures of atmofpheric air, im- 

 pregnated with four ounce meafures of carbonic acid gas, from 

 the carbonate of lime and fulphuric acid. The fixed air difap- The carbonic 

 peared, and the atmofpheric air was fo much increafed in purity, *™ d ^^"0*-' 

 as to devour two meafures of nitrous air. tion of oxigen in 



The leaves of thefe plants, kept over night in the fame air, ^ ™*^ e was 

 gave carbonic acid gas in the morning ; and its purity, in every in the dark the 



inftance, was confiderably diminifhed. leav <* produced 



_, , ■'- . - _ f , . . . _ carbonic acid 



The leaves of mimola virgata and amygdalus perfica, were gas , 



alfo feparately expofed nine hours to the influence of folar Other leaves ex- 

 light, in forty ounce meafures of atmofpherical air, in which ^ ith th e ff rm ' er 

 fixed air had been formed by leaving a fungus to putrefy it. refult. 

 The carbonic acid gas disappeared, and the purity of the at- 

 mofpherical air was increafed from SO to 80. 



IV. The following Tables ivillfheto the Quantity and Purity o^Table of experi- 

 oxigenous Gas, obtained by expofing a fmall Handful of the mtntson leaves 

 Leaves of Plants to the Light of the Sun, in forty Ounce Mea- ^j. umier 



fares of Pump Water. pump water. 



This water was taken from a well funk within a few yards of 

 a neceflkry, from which it was impregnated with carbonic acid 

 gas, as appeared from an analyfis. The leaves were feparately 

 expofed in glafTes arranged near each other, and from eight to 

 thirteen comparative experiments were made at one time. 



Leaves 



