?Inert, irregularly shaped granules of various refractory materials used to promote smooth boiling and retard bumping by providing numerous points for formation of small vapor bubbles

Inert, irregularly shaped granules of various refractory materials used to promote smooth boiling and retard bumping by providing numerous points for formation of small vapor bubbles

 

stones are silicon carbide; random size pieces up to 2 mm long. Black color prevents confusion with other crystalline materials such as digestion agents.