Dephlogifticated Air. 269

whole process the liquor had acquired a yel-lowish colour.

This experiment was made on the 19thof September 1777, and looking at the al-kaline liquor on the 14th of December1778, I observed that a white matter wasdeposited from it; but whether this camefrom the air that was decomposed in it, ornot, I do not pretend to say.

SECTION XXVII.

Various Observations relating to the Diminu -tion of common Air.

i. Of the Purity of Air in different Cir-cumfances.

W HEN I first discovered the pro-perty os nitrous air as a test of thewholesomeness of common air, I flatteredmyself that it might be of considerablepractical use, and particularly that the airof distant places and countries might bebrought and examined together, with greatease and satisfaction ; but I own that'hitherto I have rather been disappointed in

my