Re: Ah well...
A tiny amount of phenolphthalein on the water would have a more decisive effect.
Aye. As (allegedly) our (deeply unpopular) chemisty teacher found out. He drank his coffee black and always came to a lesson with a full mug..
But we didn't contaminate the urn for the whole of the staff room - we liked some of the teachers..
It was our lab-tech that was the mad one - we nicknamed him "put a bit more in" after we, with his assistance, melted the ceiling tiles by somewhat supersizing the thermite experiment.
School chemistry labs do seem to attract the odd sorts.