[ xlix ] 



that thus the quantity of dephlo- 

 gifticated air necelTary for one mi- 

 nute will now ferve for breathing 

 during half an hour, and thus the 

 expences will be thirty times lefs. 



We confume, in the fpace of 24 

 hours, about 21600 cubic-inches of 

 air. One pound of nitre yields by 

 heat about 12000 cubic-inches of 

 dephlogifticated air, and thus it 

 yields more air than any patient 

 could confume by breathing this 

 beneficial air the whole day (for we 

 muft allow at leaft 1 2 hours in the 

 24 for fleoping and necelTary occu- 

 pations), becaufe this quantity will 

 ferve thirty times longer by the 

 method explained, than in the or- 

 dinary way. It follows by this, 

 that the expences required for 

 breathing a whole day dephlogifti- 

 d cated 



