[ 5* ] 

 thofe mifchievous exhalations be- 

 ing, very providentially, fpecifically 

 lighter than common air, rife at 

 the fame time up ; and thus the 

 lower region, in which we breathe, 

 is freed from them almofl: as foon as 

 they are produced ; whereas the de- 

 phlogifticated air iifuing out of the 

 plants in great abundance in the 

 day-time is fpecifically heavier than 

 common air, and is therefore in- 

 clined to remain longer among us, 

 and to afford us all the benefit for 

 which the Supreme Wifdom has 

 providentially deftined it. 



SEC- 



