OCR Text |
Show Properties of Gold. Pnro poh' t" ;t ir.f?-ctod by tho atmosphere at-mosphere cither nt ordinary temperatures tempera-tures u. . ':iaal ts ncatcd. It Is also proof a -ainst tho action of common com-mon acids when used singly. Moreover. It ccnfer3 Its properties moio or iewupon copper and silver when theso metals are alloyed with It. Thus, for example, 12-karat gold will withstand the action of nitric acid and tho atmosphere at ordinary temperature, tempera-ture, but somo of tho copper will bo oxidized during annealing. Nino parts of gold may bo alloyed vlth ten parts of platinum tn an ordinary cruclblo and fire, but such nn alloy will not bo uniform; a larger proportion of platinum plati-num will free Itself from tho gold on solidification and a homogeneous alloy ot tho two metals cannot bo obtained.' Jewelers' Circular Weekly. |