In message , Andrew Gabriel
writes

Come to think of it, we all made a test tube of TNT in
practical chemistry when we were covering it. ISTR we had
to keep the test tube running under a cold tap to ensure
it didn't heat up. At the end of the class, it was poured
down the sink. Someone's TNT exploded when it was poured
into the sink -- there wasn't enough to do any harm, but
it sure got everyone's attention. In discussing it afterwards,
the teacher suspected there was a trace of some other
chemical in the sink which had triggered the "rapid
decomposition of tri-nitro-toluene" as he referred to it.

I thought TNT being a high explosive required percussive ignition.
According to my grandfather, who was an industrial chemist, it's quite
stable stuff otherwise.
--
geoff