What flammable materials do dragons use to breath fire?

Dragons have five lungs. The dorsal lung has become a fluid filled chamber dedicated to the storage of the flammable liquid of the true dragons (true drags, fire drags, or higher dragons). This liquid is a combination of phlegm and an assortment of heavily nitrated compounds. Sampling of this material has proven difficult as it is in the habit of spontaneous combustion on being exposed to area and heavy metal catalysts, and due to the fact that it is store inside of a dragon (enough said.) Eye witness descriptions makes it akin to Napalm and gasoline in properties.