The free acid, which is obtained by treating the salts with acids, is an oily liquid smelling like prussic acid; it is very explosive, and the vapour is poisonous to about the same degree as that of prussic acid.
The first three will he treated here; for the others see Prussic Acid and Cyanamide.
About the same time he showed by a wonderful series of experiments that the colouring matter of Prussian blue could not be produced without the presence Of a substance of the nature of an acid, to which the name of prussic acid was ultimately given; and he described the composition, properties and compounds of this body, and even ascertained its smell and taste, quite unaware of its poisonous character.
With these exceptions, the simple cyanides are readily decomposed even by carbonic acid, free prussic acid being liberated.
It is by no means the most powerful poison known, for such an alkaloid as pseud-aconitine, which is lethal in dose of about 1/200 of a grain, is some hundreds of times more toxic, but prussic acid is by far the most rapid poison known, a single inhalation of it producing absolutely instantaneous death.
