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a little elevated. In this pofition 

 the fprigs of mint grew very well, 

 and in fome of the phials he ob- 

 ferved a quantity of air to be col- 

 lected, though very flowly ; but he 

 was much difappointed, that fome 

 of the moil vigorous plants pro- 

 duced no air at all. At length, 

 however, from about ten plants he 

 collected, in the courfe of a week, 

 about half an ounce-meafure of air, 

 which he found fo pure, that one 

 meafure of it and one of nitrous 

 air occupied the fpace of only one 

 meafure. 



This remarkable fact contributed 

 not a little to confirm his faith in 

 the hypothecs of the purification 

 of the atmofphere by vegetation ; 

 but he did not enjoy this fatis- 

 faction long; for, as he found that 

 other plants of the fame fpecies. 

 i produced 



