[ xiv ] 

 ourconftitution. The moft adivc 

 poiibns which are known do not 

 fo quickly deilroy the life of an ani- 

 mal as the want of air, or the 

 "breathing of it when it is rendered 

 highly noxious. It will appear in 

 this work, that thofe very plants, 

 which, influenced by the light of 

 the fun, repair the injury done to 

 this fluid by the breathing of ani- 

 mals, and by many other Caufes, 

 , may, in different circumftances, poi- 

 fon fo much this very element, as 

 to render it abfolutely unfit for re- 

 fpiration, and, in Head of keeping up 

 life, to extingmfh it in a moment. 

 Therefore this univerfally-diffufed 

 element deferves not only the pur- 

 fuit of philofophers, but claims 

 more immediately the attention of 

 thofe whofe pr ofellion it is to preferve 

 health and to cure difeafes. I have 



beifawed 



