so On air heated, &c. 



aiid fureft manner, by means of iron only, without any 

 mixture of iulphur. To do this I fill phials with turn- 

 ings of malleable iron, and having; then filled them with 

 water, pour it out, to admit the air of the atmofphere, 

 and in fix or feven -hours it will be diminiflied in the 

 fame proportion as by iron filings and fulphur ; and the 

 fame iron will anfwer this purpofe I do not know how 

 long, but it will be till all the iron is converted into 

 ruft. What remains of air in the phial will be the pureft 

 phlogifticated air. Iron that is quite dry has no fuch 

 efie£t on air. 



The readieji method of procuring phlogifticated air 

 is, no doubt, by means of a mixture of nitrous air with 

 that of the atmofphere ; but it is liable to feveral ob- 

 jedlions ; efpecially that from not knowing the exact 

 quantity of nitrous air to be employed for this purpofe, 

 on account of the different ftates of each of thofe kinds 

 of air ; though I have not found that of the atmof- 

 phere to be fenfibly different, except in circum fiances 

 of which every experimenter is fufliciently apprized. 



Many of the mofi: important experiments recited in 

 thefe papers were made with a burning lens of fixteen 

 inches diameter, with which I was generoufly furnifhed 

 by Mr. Parker, who has fo much diftinguiflied himfelf 

 by his improvements in the art of grinding glafs. To 

 his liberality in fupplying me with various vefiTels made 

 of glafs, the public is indebted for a great proportion of 

 my other experiments on air. 



No. 



