Limelight

Hi all!

I'm new to this forum, but have sort of slid over here from CCS, so some may know me a bit.

I'm not exactly a newbie to lamps, pressure or otherwise, but have sort of boosted my interest in them lately.

I stumbled over a wikipedia description of Limelights, and wanted to ask here if anyone have any experience of that technique?

It would be kind of interesting to franky up a classic blowtorch and some lime and a reflector.. Anyone already tried it, or is there a flaw to the idea? (Worried the temp of a blowtorch isn't enough)

 

Fairly standard demonstration in a chemistry lesson over here - or was, anyway (I haven't taught since 1995).

Use a bunsen burner to heat a lump of quicklime (calcium oxide - CaO) and it glows a bit around the edges. You won't need sunglasses. I've no idea what the technique was in the theatre but it must have produced more light than I ever did in the laboratory...

 

Hmm, the diagram at wikipedia shows the use of a hydrogen/oxygen mix to produce the flame. I guess that suggests that a bunsen burner, or blowlamp, or propane burner isn't enough to produce the brighter light. A pity, but thanks for the quick response!

(link to wikipedia: http://en.wikipedia.org/wiki/Limelight)

 

My understanding is that the hydrogen/oxygen mix is part of the chemical reaction that produces the light (in addition to being the heat source).

I recall that there are some videos regarding limelight on YouTube.

I'm with you in that I'd love to gin up a rig to play with.

 

Al, I don't think there is any chemical reaction involved other than the usual one between the oxygen and the fuel. Sometimes they used other stuff than the hydrogen to make the required flame.
It's just plain old heat that makes the bright withe light.
But you must come very high to get a serious light to speak of. Around 2000ºC as I understand it from a quick Googling.

 

Oo-er, you'd need to be careful with that...

 

If you go to the Guild site http://www.lampguild.org/Default.html?Defaulttext.html&1 and do an archive search in the Q&A page for limelight there are a few posts there on the subject and a couple of illustrations. ::Neil::

 

Thanks for that link. The lampguild had some interesting bits of info.

Previously I stumbled on another page saying that "the main disadvantage was that the operator had to pay constant attention to the administration of gas, and turning the deteriorating piece of lime."

That together with the use of hydrogen sounded like a showstopper... but who knows, it might be a fun weekend project some time in the future if I find the right parts first. Thanks all!