(London, Harrison and Sons, 1886 a. 1889). 4to. No wrappers as extracted from "Philosophical Transactions" 1886 - Vol. 177 - Part II. Pp. 423-436 a. 2 plates. 1888, vol. 179 - A. Pp. 547-570 a. 4 plates, textillustrations.
First printing of both papers. "He (Abney) occupied himself a great deal with photography, photochemical processes, the chemistry of photographic developers and intensifiers, photometric investigations of the law of density of photographic plates, and spectroanalytical work. Importent are his experiments on solarization and the connection of exposures and the intensification of photographic silver bromide gelatine plates."(Eder History of Photography", pp. 454-55).