 While the first was acknowledged by Sidebotham, the latter were disputed by him indicating the fact that the 1860 gold medal for the best landscape photography was made with a Collodion-Albumen plate (Recreative Science, 1861 P 43).There are several compounds unstable to light in this mixture, mainly silver iodine and silver bromide.These decompose and leave silver that is oxidized by the developer (Pyrogallic Developing Solution).