What principle distinguishes an elixir from a syrup?

An elixir is distinguished from a syrup primarily by its alcohol content. Elixirs are typically clear, flavored liquids that contain a significant amount of alcohol, which acts as a solvent for the active ingredients and helps preserve the formulation. This alcohol content allows elixirs to dissolve both water-soluble and alcohol-soluble components, making them effective for certain types of medications.

On the other hand, syrups are primarily sweetened solutions that contain a high concentration of sugar, and they generally do not contain significant amounts of alcohol. The sugar in syrups not only provides sweetness but also contributes to the viscosity and palatability of the solution, making them suitable for a different range of applications compared to elixirs.

Thus, the defining characteristic distinguishing an elixir from a syrup is the presence of alcohol in elixirs, which is key to their formulation and function.