[ xxxviii 



it/elf has no power to mend air with- 

 out the concurrence of plants, but on 

 the contrary is apt to contaminate 

 it. 



Thefe are fome of the fecret 

 operations of plants I difcovered in 

 my retirement, of which I will en- 

 deavour to give fome account in 

 the following pages ; fubmitting, 

 however, to the judgement of the 

 candid reader the confequences, 

 which I thought might fairly be 

 deduced from the facts I am to 

 relate. 



I muft not omit to acquaint the 

 reader, that, in purfuing the experi- 

 ments related in this work, he will 

 find that he labours in vain, if he does 

 not make ufe of pump- water fre in- 

 ly drawn ; for if this water has 

 been expofed to the open air during 

 fome time, it will have parted with 

 5 a great 



