( 5° )

If ; because Lead, as soon as it melts, Im-mediately begins to calcine into Ashes;but, as soon as any Phlogiston is thrownupon them, they are immediately broughtinto their pristine metalline State again.The Truth of this may be made apparentby an easy Experiment; take a Piece ofLead, free from Dross, put it into a deanCrucible, and smelt it in a moderate Fire,there will first arise on the Metal a thinSkin or Cuticle, which soon after will turnto Ashes • throw upon them, while theyare swimming upon the Metal, some Oil,©r the Fat of any Animal, and the Asheswill be instantaneously reduced into Leadagain.

The Phlogiston made use of in largeFurnaces) must, as has been observed, bewithout Acid ; but any Fat, Grease, andWood-charcoal, or Wood-charcoal alone,may be substituted. This I intend as aHint for those Smelters, who, following,the common Practice of the Country, use,for this Purpose, small Pit-charcoal, mixedwith Lime; but, as I am satisfied, thatthe Acidity in these Fossils must be detri-mental to the Smelting of the Ore, Iwould advise them to take small Wood-charcoal in their stead, particularly as noconsiderable Quantity is required.

Stbly, It is absolutely necessary that theSmelters should refrain from the Use of

Lime