or prussic acid. Acid composed of cyanogen and hydrogen, extremely toxic for organisms and animals: if inhaled in a gaseous state, it may provoke an almost instantaneous death (mortal dose for humans: 0.5 grams). Other than diffused as rat poison, it was once used for the disinfestation of wooden supports and thus substituted other insecticides due to its extreme toxicity (see Methyl Bromide). However, because it is soluble in water, this presents a contradiction as it is to be retained in wood that always contains a certain natural humidity.