St. Peter's Square, Vatican City, Vatican, seen through the Balustrade atop the Basilica. Photo by Elisabetta Villa/Getty Images News/Getty Images. Definition: A balustrade is a row of repeating balusters-small posts that support the upper rail of a railing.Staircases and porches often have balustrades. balustrade is a row of repeating balusters-small posts that support the upper rail of a railing.
dissociation, in chemistry, separation of a substance into atoms or ions. Thermal dissociation occurs at high temperatures. For example, hydrogen molecules (H. The Columbia Electronic Encyclopedia, 6th ed. Copyright Â© 2012, Columbia University Press. All rights reserved.
The term sublimation refers to a physical change of state and is not used to describe transformation of a solid to a gas in a chemical reaction. For example, the dissociation on heating of solid ammonium chloride into hydrogen chloride and ammonia is not sublimation but a chemical reaction.