VERBESSERUNG HINSICHTLICH DER UEBERWACHUNG VON PHYSIKALISCHEN ODER CHEMISCHEN AENDERUNGEN IN EINEM GASTMATERIAL

Disclosed is a method of monitoring physical and chemical changes in a host material which passes from a liquid state to a solid state. A waveguide is embedded in the host material while it is in the liquid or uncured state, the waveguide extending outside of the host material. A sound wave is sent through the waveguide and is monitored after it has passed through the host material. An article is also disclosed of a container having a liquid sealing exit means for waveguide, a waveguide which passes through the liquid sealing exit means into the container, a solidifiable liquid in the container at a level above the liquid sealing exit means, means outside the container for sending an acoustic wave through the waveguide into the container, and means outside the container for monitoring the acoustic wave after it has passed through said waveguide into the container.