462 On phlogiston. 



tains more than fifty grains of mercury, makes twelve 

 ounce meafures of inflammable air difappear. 



It is a difficult matter to be exa£t in this experiment, 

 for fome of the precipitate always difperfes in reviving the 

 mercury, and a part of the metal fublimes and adheres to 

 the fides of the veflTel which is ufed. 



As 1 believe, that when a metallic calx is heated in hy- 

 drogenous gas, the oxygen of the calx, unites to the hy- 

 drogen and forms water, I always calculate from the quan- 

 tity of hydrogenous gas that difappears, from heating a giv- 

 en quantity of a calx in this air. 



According to my experiments, one ounce of red preci- 

 pitate, mercurius precipitatus per fe, and the calx obtained 

 by boiling a folution of cauftic pot-afh on turbith mineral, 

 makes 1 1 2 ounce meafures of inflammable air difappear, 

 when heated in it by the burning lens. 

 Red Lead 88 

 Mafficot 3 2 

 Litharge 33 

 Manganefe 192 

 Copper 144 

 Iron 288 



Upon diifolvlng half a drachm of the precipitate of iron, 

 which had made fixteen ounce meafures of hydrogenous 

 gas difappear, in diluted fulphuric acid, as much inflam- 

 mable air was obtained, as two grains of the filings of mal- 

 leable iron would have produced. According to this 

 experiment, were I to calculate in the fame manner as Dr. 

 Prieftley, I would fay, that one ounce of bar iron abforbs 

 3840 ounce meafures of inflammable air, but this quantitv 

 of the metal by folution in the fulphuric acid and water will 

 yield no more than 365 ounce meafures of hydrogenous 

 gas. 



If an ounce of mercury abforbs 362 ounce meafures of 

 inflammable air, it ought to give out this air when diflTolv- 



ed 



