ATMOSPHERICAL OXtGEN. 



fill 



XVIII. 



Experiments proving the Necejfity of atmojpherical Oxigtn in the 

 Procefs of Vegetation. In a Letter from Mr. John Gough. 



To Mr. NICHOLSON. 



SIR, 



JLJR, Prieftley and M. Ingenhoufz have made many experi- Rcfleftionson 



ments with plants, confined in azote; from which philofophers ^^"^"^^ '7'^" 



have inferred, that vegetables differ from animals in not requir- kind. 



ing the prefence and fupport ©f atmofpherical oxigen. One 



circumftance however occurs in all thefe experiments, if my 



memory be correal, which renders the conclufion doubtful: 



the plants, ufed in them were in conta6t with the water that 



confined the azote in the inverted jars, through the medium of - 



which they had evidently the fame indirect communication 



with the atmofphere that fifties are known to require. 



With a view to throw fome additional light upon this dif- Experiments o« 

 putable point in the ,iFegetabIe economy, I determined to fur- J"^cculentvcgc- 

 round certain fucculent plants entirely with azote; which pof- 

 fefs the Angular property of vegetating when fufpended by the 

 roots in dry air. My method of performing this confifts in fix- 

 ing the fubje€l of the experiment by means of a thread, to a 

 fmall perforated board, landing on a pillar, which was fur- 

 •ifhed with a foot of lead. The plant being thus fecured, was 

 introduced through water into a glafs jar of azote; where it 

 was wholly furrounded by the gas. 



Exp. 1, The firft experiment, I made in this manner, was Experiment with 

 tried in June 1 800. A plant of fedum acre was furrounded by ^^^""^^^^^ ^°'"* 

 aeote when it was ready to expand its flowers, and another 

 was placed befide it, under a fimilar jar 5 which contained 

 3 common 



to flower. 



