2'8S Dr. Priestley's Experiments and Obfervations 



Having had this fuccefs with the calx, or icales of iron, I 

 tried the calx of copper^ or thofe fcales which fly from it when 

 it is made red-hot ; and I found water produced in the inflam- 

 mable air in the fame manner as when I ufed the fcales of iron 

 in the fame circumflances. I alfo had the fame refult when I 

 Yewived. precipitate per fe m inflammable air; but having at that 

 time a very weak winter's fun, I could not make the experi- 

 ment with fo much advantage as I could have wiflied. 



Iron, I found, acquired this additional weight by melting 

 in an earthen retort, as well as in the open air by the fun- 

 beams, if it were pofTible for it to attract air, or whatever elfe" 

 it is that is the immediate caufe of its additional weight. 

 Three ounces of common iron filings, expofed to a flrong heat 

 in an earthen retort, gained 1 1 dwts, or 264 grains, and yet 

 was very far from having been completely fufed. Having a 

 glafs tube communicating with the retort, in order to collect 

 any air that the iron filings might give out, I found that when 

 they were very hot, the water alcended within the tube ; which 

 fhews that the iron was then in a ftate of abforbing, and not' 

 of giving out any air. 



Seeing (o much water produced in thefe experiments with 

 inflammable air, I was particularly led to reflect on the relation 

 which they bore to each other, and efpecially to Mr. Cav^.n- 

 dish's ideas on the fubje6l. He had told me that, notwith- 

 ftanding the experiments of which I had given an account to^ 

 the Royal Society, and from which I had concluded that in- 

 flammable air was pure phlogifton, he was perluaded that wafer- 

 was eliential to the produclion of it, and even entered into if 

 as a conftltuent principle, x^t that time I did not perceive the' 

 force of the arguments which he flated to me, efpscially as, iit' 

 the experiments with charcoal, I totally difperfed any quantity 



of 



