[ 57 2 1

metal seems to shew that the fire has produced Its fulleffect, platina has been always found to retain so much ofthe lead as to break under the hammer; yet by continuingthese vehement fires for twenty hours or more, so much ofthis retained lead is separated, as to leave the platina mal-leable. Much of the lead was forced out after the metalhad become solid, as appears in the experiment, No. 17,in which the quantity expelled from the cupelled plates.,without their having anywise softened or altered theirfigure, amounted to above a tenth part of their weight.The thinner the metalline plates, the sooner and moreeffectually were they freed from the lead, and renderedmalleable: in one cupellation, a part of the metal havingrun into the form of a fine wire, this wire, after six hoursstrong heat, proved so flexible, as to bear bending back-wards and forwards several times without breaking, whilea thick piece of the fame mass, after eighteen hours longercontinuance of the sire, was still brittle : when a smallquantity of platina, worked in a cupel of a proportionatesize, had, from the shape of the vessel, formed a prettythick mass, which was the cafe in most of the first cupel -lations (No. 1 to 8 of this article) a vehement fire, ofmuch longer continuance than that of Macquers experi-ment, was insufficient for rendering the. mass malleable;but when beaten into powder and spread thin, a fire not ex-tremely vehement, continued ten or twelve hours, madethe particles of the powder so ductile, that they stretchedunder the pestle into fine plates like fragments of silverleaf: the powder thus flatted was remarkably soft orunctuous to the touch, like talk; and being rubbed onpaper, stuck to it, so as not to be easily brushed off,.makingit look like what. is called silver paper. It was therefore ahappy circumstance in Macquers experiment, and indeedessential to its success, that he used a considerable quantity