458 On phlogiston. 



the new fyftem of chemiftry, are compoled of eighty- 

 feven parts of oxygen and thirteen of hydrogen, which is 

 nearly (even times as much of the former as of the latter, 

 there mull be a great depofition of oxygen fomewhere, 

 when iron is diffolved in the diluted fulphuric acid, which 

 he cannot difcover. 



He denies that it unites to the metal, and declares there 

 is no addition of oxygen in the procefs, and confequently 

 that there is no decompofition of water in the cafe. 



That there is a quantity of oxygen, which unites to the 

 metals, when diffolved in acids, I think can be eafily 

 proved. 



In order to do this I will fhew, that when pure metallic 

 calces, which are acknowledged by Dr. Prieftley to contain 

 oxygen, are heated in hydrogenous gas, that the oxygen 

 of the calces unites to the hydrogen and forms water, and 

 that the difappcarance of the inflammable air, is always in 

 ftridl proportion to the pure air, which the calces contain. 

 I will then prove that the calces of copper and iron, ob- 

 tained from the fulphates of thefe metals by ammoniac, 

 have this property of making large quantities of inflam- 

 mable air difappear. The oxyds which are acknowledged 

 to contain oxygen arc mercury, lead and manganefe. 



The focus of the lens was thrown upon two drachms of 

 red precipitate, confined in thirty-two ounce meafures of 

 hydrogenous gas, obtained from the fulphuric acid diluted 

 with water and the filings of bar iron, and which had been 

 well wafhed in lime water. Twenty-two ounce meafures 

 of the inflammable air diiappeared, the mercury was reviv- 

 ed and no carbonic acid gas was produced. The air which 

 remained behind was not altered. 



According to Dr. Priefl;Iey, fixed air fhould have been 

 formed in this procefs, for he fays, when any fubftance 

 known to contain oxygen, is heated in inflammable air, 

 fixed air is found, but this is not the cafe, 



I 



