C 264 ] 



known, your philosophical refearches bad not then 

 made you acquainted with that mod remarkably an- 

 tifeptic property of nitrous air. Since you favoured 

 me with a view of fome aftonilhing proofs of this, I 

 have conceived hopes, that this kind of air may like- 

 wife be applied medicinally to great advantage. 



W. H. 



A Correction, 



Upon re-examining Dr. Hales's account of his 

 experiments to meafure the diminution of air by re- 

 fpiration (Statical Eiiays, Vol. I. p. 238, 4th edition), 

 I find an error of the prefs, of ^for ^ T 3 fo that the 

 diminution of air by refpiration, though very various, 

 is, I believe,, always considerably Jefs than by putre- 

 faction, or feveral other caufes of diminution. But 

 though 1 have mentioned this diminution as equal to 

 feveral others, nothing material depends upon it ; 

 the quality of the air thus diminifhed being, in all. 

 refpe£ts, the fame, notwithstanding the cauie of in- 

 creafe (which, as I have obferved, in this and other 

 cafes, co-operates with the caufe of diminution) be 

 greater than I had iuppofed. 



I did not endeavour to meafure the quantity of the 

 diminution of air by refpiration, as 1 did that by. 

 other caufes ; becaule I imagined that it had been 

 done fufficiently by others, and efpecially by Dr», 

 Hales. 



XX. An 



