Treatise on Poisons by Sir Robert Christison

2. _When diluted_, it is recognised with facility, first by

litmus-paper, and then by the nitrate of silver, which forms with it a dense, white precipitate, the chloride of silver. This is soluble in ammonia, reappears on neutralizing the ammonia by nitric acid, and is not redissolved by a large excess of nitric acid, even aided by heat. Its permanence under an excess of nitric acid distinguishes it from every other silver salt, but the cyanide; which again is known by disappearing when boiled with a large excess of the acid.