Great care must be taken in the use and determination of cyanides owing to their highly poisonous nature.

* Analytical grade potassium chloride or sodium chloride, dried at 110-120 °C, is suitable.

Discussion. This anion may be determined as silver cyanide, AgCN, the experimental details are similar to those given for chloride, except that, owing to the volatility of hydrocyanic acid, the solution must not be heated. The cold solution of alkali cyanide is treated with a slight excess of silver nitrate solution, faintly acidified with nitric acid, the precipitate allowed to settle, collected on a weighed filtering crucible, and weighed as AgCN after drying at 100 °C.