WELCOME BACK TO WAR! good morning worldwide! Another chemical gas warfare agent : Hydrogen Cyanide ! Preparation: All work MUST be done in a ventilated hood! To the round bottom, flask fitted with dropping funnel and gas outlet tube 100 g carbonate-free potassium cyanide are placed. The gas outlet tube leads to two U tubes in series which are filled with a mixture of fused and granular calcium chloride, and immersed in a water-bath at 35° C. The second of these U tubes may be connected to two more U tubes, the first of which is maintained at about — 10° C in a freezing mixture and the second at + 20° C. Each of these tubes, which are designed to receive the condensate of hydrogen cyanide formed in the reaction, is fitted at the bottom with a glass lead-off tube. This is connected through a glass cock to a cooled flask in which the liquid hydrogen cyanide collects. Before the synthesis a current of dry air is passed through the whole of the apparatus. Cooled aqueous sulfuric acid (1 : 1) is allowed to drop slowly through the dropping-funnel on to the potassium cyanide, regulating the rate of addition so that 1 drop of hydrogen cyanide condenses in the first receiver every second minute. Towards the end of the reaction it may be necessary to gently heat the contents of the flask. The greater part of the hydrogen cyanide produced in the reaction condenses in the first U tube and is collected in the corresponding flask. Pure anhydrous hydrogen cyanide is a clear colorless liquid with a peculiar odor of bitter almonds. It boils at 26.5° C, and solidifies on cooling at — 13.4° C, forming a crystalline mass which melts at — 15° C.