Anti-bumping granules

These are small ceramic granules which have rough edges. A few are added to a liquid before heating and they encourage smooth boiling. Four or five granules is enough to work well - students often add ten times this amount!

During boiling the bubbles of vapour form around rough areas. If a liquid is boiled in very clean, smooth glassware it can be difficult for bubbles of vapour to form. Suddenly, one large bubble of vapour forms disturbing the boiling liquid violently. This effect is known as bumping, and is hazardous.