DuPont Sporting Powders, multicolor design on 1910 cover showing Quail on Rail Fence & Cornfield, franked with 2¢ Washington-Franklin (with Du Pont prefins) tied by Denver, Colo. Jun 13 machine cancel to Golden, Colo., inscribed at bottom left "E.I.Du Pont de Nemours Powder Co." return address, Extremely Fine, this is the only example we have offered with this return address. Estimate  $200 - 300. $0 (Image)