148 Mr. Cavenpisn’s Experiments on Air. 
is phlogifticated ; whence it is natural to conclude, that the 
light enables the dephlogifticated part of the air to abforb 
phlogifton from the tincture ; and this appears to be really the 
cafe, as 1 find that the air in the bottle 1s confiderably phlogif- 
ticated thereby. Dephlogifticated {pirit of nitre alfo acquires a 
yellow colour, and becomes phlogifticated, by expofure to the 
fun’s rays *; and 1 find on trial that the air in the bottle in 
which it is contained becomes dephlogifticated, or, in other 
words, receives an increafe of dephlogifticated air, which fhews 
that the change in the acid is not owing to the fun’s rays com- 
municating phlogifton to it, but to their enabling it to abforb 
phlogifton from the water contained in it, and thereby to pro-= 
duce dephlogifticated air. Mr. ScHEELE alfo found, that the 
dark colour acquired by luna cornea on expofure to the light, 
is owing to part of the filver being revived; and that gold, dif> 
folved in aqua regia and deprived by diftillation of the nitrous 
and fuperfluous marine acid, is revived by the fame means; 
and there is the utmoft reafon to think, that, in both cafes, the 
revival of the metal is owing to its abforbing phlogifton from 
the water. 
Vegetables feem to confift almoft intirely of fixed and phlo- 
gifticated air, united toa large proportion of phlogifton and fome 
water, fince by burning in the open air, in which their phlogifton 
unites to the dephlogifticated part of the atmofphere and forms 
* If fpirit of nitre is diftilled with a very gentle heat, the part which comes 
over is high coloured and fuming, and that which remains behind is quite colour 
lefs, and fumes much lefs than other nitrous acid of the fame ftrength, and the 
fumes are colourlefs. This is called dephlogifticated fpirit of nitre, as it appears 
to be really deprived of phlogifton by the procefs, The manner of preparing it, 
as well as its property of regaining its yellow colour by expofure to the light, is 
mocntioned by Mr. ScHEELE in the Stockholm Memoirs, 1774. 
water, 
