I repeated to heat up hexamine and KNO₃ in a test tube. Beside the weak odor of HCN I found a strong odor of NH₃ (ammonia).

As I have already the theory in getting KOH I played a little bit to find a stoichiometric equilibrium:

(CH₂)₆N₄ + 3 KNO₃ --> 3 KOH + 3 NH₃ + C₂(CN)₄ + 3 O₂ (I need to make a glowing splint test)

or

(CH₂)₆N₄ + 3 KNO₃ --> 3 KOH + 3 NH₃ + C₆N₄O₆

C₂(CN)₄ is called Tetracyanoethylene (TCNE). TCNE hydrolyzes in moist air to give hydrogen cyanide, which would explain the odor of HCN!

For C₄N₃O₆ I got not much information. It seems to have 3 different possible structures with an unspeakable name: http://www.chemspider.com/Search.aspx?q=C6N4O6&rid=cfef353a-d62f-46c6-8c...

Sure, other reaction products would be possible.

Author: M. Bindhammer, Team Selene