Fixed Air on Vegetation. 363 



fatisfaftorlly proved, eight years fince. On 

 this occafion, therefore, I thought it not improper 

 to recur to my journal of experiments, and to 

 take this method of laying an account of them 

 before the Literary and Philofophical Society; 

 in order to afcertain your claim to the difcovery 

 in queflion. 



In regard to the animal body, it would furely 

 be wrong to fay that nothing was nutritious or 

 falutarv to ir, but what it could bear to receive 

 unmixed or undiluted. Why then may we not 

 fuppofc that though fixed air^ when pure, 

 may be fatal to plants confined in it j and ex- 

 cluded from free communication with the com- 

 mon air, yet when applied in proper dofe, and to 

 plants enjoying a free intercourfe with the atmo- 

 fphere, it may have a contrary effedl, and ferve 

 to nourifh and fupport them ? 



But in Dr. Pricftley's experiments, this free 

 intercourfe does not appear to have been allowed j 

 and herein, I apprehend, confifled the caufe of 

 the difference in our refulcs. 



At that time, the conftitution of fixed air was 

 not underflood. It is now, generally, allov/ed to 

 be formed by a combination of phlogifton with 

 the pure part of acmofpheric air. The firft of 

 thefe ingredients has been proved, by the expe- 

 riments of Dr. Pricftlcy and others, to be favour- 

 able to vegetation, while plants droop and decay 

 Vhen expcfcd to the adion of the latter. It 



iliould 



