4l5o On phlogiston. 



Some manganefe was alfo precipitated from its folution, 

 in the muriatic acid by ammoniac, and when frefh made 

 it would never make any inflammable air difappear, when 

 heated in it by the burning lens, but after being expofed a 

 few days to the a(5lion of atmofpheric air, one drachm of it 

 made four ounce meafures of inflammable air difappear. 

 In all thefe cafes we evidently fee the operation of oxygen. 

 Not knowing the exadt quantity of pure air, which iron 

 and copper abforbed, one drachm of the filings of bar iron 

 were melted by the burning lens in oxygenous gas when 

 twenty-fix ounce meafures were imbibed by the iron, and 

 the fame quantity of the filings of copper treated in the 

 fame manner gave an abforption of thirteeen ounce meafures. 



One drachm of the precipitate of iron, from a folution of 

 the fulphate of iron by ammoniac, was then heated in for- 

 ty-fix ounce meafures of hydrogenous gas, when thirty-fix 

 ounce meafures of the air difappeared. 



The fame quantity of the common ruft of fteel, and the 

 carbonate of iron, obtained from green vitriol by a foluti- 

 on of mild pot aih, and what Dr. Prieftley calls a nitrated 

 calx of iron, formed by adding nitric acid to a calx of iron and 

 expofing it to a red heat, when treated in the fame manner, 

 made exadlly as much air vanifli. 



One drachm of the precipitate of copper, from a foluti- 

 on of blue vitriol by ammoniac, expofed to the adtion of 

 the lens in hydrogenous gas, made eighteen ounce mea- 

 fures of the air difappear. 



Here then are two metals, one of which the iron, ab- 

 forbs twice as much oxygen, when melted in it, as the cop- 

 per, and its calx following the fame proportion when heat- 

 ed in hydrogenous gas, makes exactly twice as much of 

 the air difappear. 



After one drachm of the calx of iron, had made thirty- 

 fix ounce meafures of inflammable air difappear, it was 

 expofed to the a^ion of the lens in oxygenous gas, when 



four 



