Explosion in fume cupboard damages several laboratories

An explosion occurred in a busy university laboratory during a few minutes when it happened to be unoccupied. The explosion was puzzling since the laboratory was dedicated to geochemical work, such as digesting rock samples with stable, inorganic reagents. The only unstable substance knowingly stored or handled for this purpose, perchloric acid, was not in use on the day of the incident. The investigation was unable to reach an exact conclusion but did prove that a substantial organic contaminant, not on the laboratory inventory, must have been present