A controlled explosion of school lab supplies has taken place in Dublin's St Stephen's Green this morning.
The nitric acid became unsafe at a nearby school.
At around 5 o'clock this morning, Gardaí and the Army Bomb Disposal team were called to St Stephen's Green.
The acid is found in school science departments around the country - it deteriorates overtime and becomes unsafe if it crystallizes.
The army said it carries out about 10 controlled explosions on the substances each year.
It said the operation was routine and there are no safety concerns for pupils.