37 



seen that their results are altogether opposed to the 

 notion that plants, by their vegetation, purify the 

 air ; and these experiments have been so often re- 

 peated, and with such uniformity of result, as to im- 

 press us with an entire confidence in their truth. 

 We proceed, therefore, to investigate the actual 

 changes which atmospheric air undergoes in vegeta- 

 tion ; and, first of all, the effects produced on its 

 nitrogenous portion. It has been already shewn, 

 that seeds (5.) do not in the smallest degree germi- 

 nate in nitrogen gas : and Dr Ingenhousz proved, 

 also, by experiment, that, in pure nitrogen gas, 

 plants do not grow. This conclusion has been more 

 lately confirmed by the experiments of Mr Gough. 

 He confined several succulent plants in jars of ni- 

 trogen gas when their flowers were just ready to ex- 

 pand ; but they died away without putting forth any 

 of their blossoms. Others were placed in similar 

 situations before the flower-buds formed upon them, 

 but made not the least effort towards vegetation ; 

 and many more, which grew very well in inverted 

 jars of atmospheric air, ceased to vegetate when 

 transferred into jars of nitrogen gas. But this gas, 

 although it does not aid vegetation, appears in no 

 degree to injure the faculty of growth in plants any 

 more than in seeds (5.) ; for a slip of spearmint, 

 which had remained twelve days in nitrogen gas, 

 recovered upon being restored to the air ; and an off- 

 set of semfiervivum vegetated freely after being remo- 

 ved from a jar of the same gas, in which it had been 

 kept from the 2d of April to the 2d of May *. As 



Nicholson's Journal, November 1801, p. 218. 

 C 3 



