"Tim Streater" > wrote in message
...
> In article >,
> Reentrant > wrote:
>
>> On 14/03/2011 11:09, Bernard Peek wrote:
>>
>> >
>> > ... The type of glass pan that can be put on direct heat
>> > is a comparatively new invention.
>>
>> Maybe, but glass test-tubes and conical flasks have been used over Bunsen
>> burners for a very long time.
>
> Relatively thin glass though. And I don't think you heat them up empty. Or
> do you? - I heated a mixture of flowers of sulphur and potassium
> permanganate in a test tube once on a little burner at home. Nothing much
> happened for a while, then there was a "thunk" and all the mixture shot
> out as a plug, through the window I'd left open just in case.
>
> --
> Tim


There is a difference between oven proof and flame proof. They are made
and tempered differently.