A.-P. Martial (Adolphe-Martial Potémont, dit) (1827-1883) Lettre sur les éléments de la gravure à l'eau-forte. 1864. Complete suite of 4 etched plates [305 x 455]. Fine proofs on laid paper, the 1st very oxidized, the other three very fresh (except for a fine trace of oxidation at the edges). Some light foxing or staining. Slight dusting and minor damage to leaf edges. Filled buff vellum cover with flaps (with printed receipt: "Il a été tiré de cet ouvrage cent exemplaires sur papier de Hollande Van Gelder Zonen numérotés de 1 à 100 : n° 43" followed by a facsimile of Lefranc's initials), illustrated with an engraving on the upper cover and bearing the printed words "Lefranc & Cie" then "a. p. martial / la gravure a l'eau-forte", much faded (accidents, missing parts and tears at the edges).