28 S Dr, Priestley's Experiments and Obfeyvations 



Having had this fuccefs with the calx, or Icales of iroji, I 

 tried the calx of copper, or thofe fcales which fly from it whea 

 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 fiime circumftances. I alfo had the fame refult when I 

 Y (tyw^^^ precipitate per fe in 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 Vv'iflied. 



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 poffible for it to attra61; air, or whatever elfe 

 it is that is the immediate caufe of its additional w^eight. 

 Three ounces of common iron filings, expofed to a ftrong 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 afcended within the tube ; which 

 fliews that the iron was then in a ftate of abforblng, and not 

 of giving out any air. 



Seeing fo much water produced in thefe experiments with 

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

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

 dish's ideas on the fubjeil. 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 v/as pure phlogifton, he was perfuaded that ^uDater 

 w^as effential to the produdlion of it, and even entered into it 

 as a conftituent principle. At that time I did not perceive the 

 force of the arguments which he flated to me, efpecially as, in 

 the experiments with charcoal, I totally difperfed any quantity 



of 



