Sublimation is a term which most literary readers encounter through work influenced by Freudian psychoanalytic interpretation, but it is helpful to know that the term came to Freud from physical chemistry where sublimation names the process of phase-change from a solid to a gaseous state without passing through the intermediate state of liquidity. Experiments demonstrating sublimation often involve heating a solid (such as frozen Carbon Dioxide or Ammonium Chloride) which does not apparently liquefy but turns directly to a gas, then cooling the gas so that the solid reappears, again without passing through the liquid phase.
Freud first uses the term in his paper “ ‘Civilised’ Sexual Morality and Modern Nervous Illness” …
Editors. "Sublimation". The Literary Encyclopedia. First published 06 May 2007
[http://www.litencyc.com/php/stopics.php?rec=true&UID=1069, accessed 22 February 2017.]