A Popular Treatise on Photography . Translated By W.H. Thornthwaite. After carefully closing the shutter in front of the yellow-glass window, the plate is removed from the frame.
Pyrogallic acid is a white crystalline solid, without smell.
It is soluble in water, alcohol, and ether, and its solution in either of these menstrua becomes rapidly decomposed on exposure to the air and light, especially if the solution be alkaline. This substance alters very soon even when it is dry. If a small amount of moisture be present, however, the decomposition proceeds with increased rapidity, being expedited by the foreign matter which it contains. Upon this filter throw 15 grs. The filtration being complete the funnel is removed, and the flask stopped lightly with a cork, and set aside for use in the dark .