C 22 9 I 



The air, which I had thus diminiihed by calcina- 

 tion of lead, I transferred into another clean phial, 

 but found that the calcination of more lead in it had 

 no farther effect upon it. This air alfo, like that 

 which had been infected with the fumes of charcoal, 

 was in the higheffc degree noxious, made no effer- 

 vefcence with nitrous air, was no farther diminished 

 by the mixture of iron filings and brimftone, and was 

 not only rendered innoxious, but alfo recovered* 

 in a great meafure, the other properties of common 

 air,, by warning in water. 



It might be fufpected that the noxious quality of 

 the air in which lead was calcined,, might be owing 

 to fome fumes peculiar to that metal;, but I found no 

 fenfible difference between the properties of this air, 

 and that in which tin was calcined. 



The water over which metals are calcined acquires 

 a yellowim tinge, and an exceedingly pungent fmell 

 and rafte, pretty much, as near as Lean recollect, for 

 I did not compare them together, like that over 

 which brimftone has been frequently burned. Alfo 

 a thin and whitiih pellicle covered both die furface 

 of the water, and likewiie the (ides of the phial in 

 which the calcination was made, infomuch that,, 

 without frequently agitating the water, it grew fo 

 opaque by this conftantly accumulating incruftation,, 

 that the fun beams could not be tranfmitted through 

 it in a quantity fufficient.to produce the calcination.. 



I imagined, however, that, even when this air was- 

 transferred into a clean phial, the metals were not fo 

 eafily melted or calcined as they were in frefh air;* 

 for the air being once fully faturated with phlogifton, 

 may not fo readily admit any more, .though it be only.. 



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