The same mixture of hexamine and KClO3 was previously incombustible without adding substance X. It seems there is a correlation between the metal cation valency of the oxidizing salt and hexamine. Hexamine is indeed used as a precipitating agent for cations. It let me think if it is possible to moderate the combustion by adding specific amounts of substance X to a hexamine/ potassium chlorate or perchlorate mixture --- I mean a solid rocket engine controllable like a liquid rocket engine.
