sentences:  The novel ends with the Mesklinite colonies receiving clandestine help and communication with the Hoffmans, but it is not revealed whether Barlennan's machinations remain secret from the other humans.The main theme revolves around hard science, particularly the physics and thermodynamics of mixtures.While water should be in the form of ice at all times on Dhrawn, the effect of ammonia in the atmosphere is to cause it to become a liquid under certain conditions of temperature and pressure, because of the formation of a eutectic mixture which melts and freezes at a much lower temperature than water.