Victor Meyer apparatus

The Victor Meyer apparatus is the standard laboratory method for determining the molecular weight of a volatile liquid.

In this method, a known mass of a volatile solid or liquid under examination is converted into its vapour form by heating in a Victor Meyer's tube.

A small quantity of glass-wool or asbestos pad covers the lower end of the Victor Meyer's tube to prevent breakage, when a glass bottle containing the substance under examination is dropped to it The liquid in the outer jacket is heated until no more air escapes from the side tube.

The bottle falls on the asbestos pad and its contents suddenly change into vapour, blows out the stopper and displaces an equal volume of air in graduated tube.

The volume of air displaced is measured by taking the graduated tube out, closing its mouth with thumb and dipping in a jar filled with water.