Color plate depicts a photographer working in a darkroom. He holds a glass plate, presumably a negative, over a processing tub. The surrounding walls contain various glass vessels. The explanatory text states how the room is lighted through a window of red glass to cut out the "...chief actinic, or chemical, rays of sunlight."

This plate is from John Howard Appleton's (1844-1930) Chemistry, Developed by Facts and Principles Drawn Chiefly from the Non-Metals, published in 1884. Intended as an introduction to the study of chemistry, this volume contains illustrations throughout the text including color plates. Color plates have been digitized along with a selection of illustrations.