Photochemical camera

This tripod mounted device has an aperture to keep out light until a picture is ready to be recorded. A treated photochemical plate is slid into the camera and the aperture is opened for about a minute, or longer in dimmer conditions. Exposure to light in the presence of a certain gas causes the image to set on the plate, and a quick saline rinse ensures the image will not develop further if exposed to more light. These photographs are popular among the lower classes, who cannot afford proper portrait paintings.