^ On the transmission 



placed it as quickly as I could over a piece of hot char- 

 coal, and obferved that it burned with a confiderable 

 glow, mush better than in common air : and the jar was 

 filled with a white cloud. After a few m mutes the air 

 was diminiflied to about one-fourth of its original bulk ; 

 but after remaining in this fituation all night, it was 

 increafed to about one-third of the original quantity; 

 and being then examined, it appeared to be all phlogifti- 

 cated. Dipping the fame charcoal into water, I got from 

 it i-i ounce meafures of air, all phlogifticated, but with a 

 flight mixture of fixed air. This fubjedl may deferve 

 farther inveftigation. For fince dephlogifticated air fo 

 readily unites with nitrous air, and with it forms nitrous 

 acid, it is not cafy to account for nitrous air containing 

 any portion of the fame element, and retaining its aerial 

 form. Alfo the juice of turnfole docs not change its 

 colour by faturation with nitrous air, which if it con- 

 tained oxygen, it might be expeded to do. 



Miscellaneous Experiments. 



I . On the colouring of the folut'ion of copper in Vola- 

 tile Alkali, and of various fubjlanccs in the marine acid. 



In repeating my former experiments of this kind, a 

 few circumftances occurred which 1 did not fo particu- 

 larly attend to before ; and may be deferving of notice, 

 and of a farther profecution. They fhow that dephlo- 

 gifticated air is eflential to thefe colours, and how they 

 may be given and taken away at pleafure. 



It is well known that the folution of copper in cauftic 

 volatile alkali affumes a blue colour if it be made with 

 accefs of air. Without it, it is perfedly colourlefs ; and 

 the colour may be difcharged by more copper, and 

 reftored again by means of air, as long as the menftruum 



is 



