Has anyone tried to build a limelight before?

[kalieaire]

Yes, a real incandescent limelight using quicklime and an open (yet concentrated) flame.

As long as this is beyond flashlights, I was thinking of some real candlepower.

 

[Paul Baldwin]

I made an HHO device that kicks out a reasonable amount of gas so made a gas torch for it to play with. I also have some slaked lime left over from plastering a room out in my cottage. When you apply the flame to the lime the white light produced is intense and painfull to the eye. That's as far as I got tho, I need to fit a couple of the flashback arrestors I bought to make it not quite as exciting when trying to extinguish the flame lol

 

[Illum]

due to the reactivity of quicklime I'm not sure where to go about acquiringit or how to dispose of it.

IIRC a cake of CaO has to be heated by something to exceed 2400C before it starts glowing...kinda like an HID, a huge amount of power on initial startup followed by relatively low power to sustain

if you want a "non-reactive" form of real candlepower, try carbon arc using a 12V automotive battery and carbon rods available at welding stores

 

[Paul Baldwin]

IIRC a cake of CaO has to be heated by something to exceed 2400C before it starts glowing...kinda like an HID, a huge amount of power on initial startup followed by relatively low power to sustain

I'll try and heat a smaller chunk next time and see what happens.

 

[kalieaire]

Not quite. CaO starts emitting light at 1200C easy (which coincidentally is the upper limit for an air breathing butane/propane torch), but it's just really red and not very bright.

Propane and O2 can bring the quicklime 2200 without much difficulty, and it'll be bright.

I'm just thinking about ways of making renewable lighting.

http://www.youtube.com/watch?v=dP9m9kVBpKI

This woodgas torch interests me, skip to 6:56 and watch til the end.

Though, I'm guessing it's only barely as hot as a butane torch.

----Edit

Further research turned up that air breathing carbon monoxide can actually burn at temperatures over 2400C if gassified properly from all sources -- WOOD!

Carbon Monoxide is actually one of the primary components of wood gas!

 

[Paul Baldwin]

Feel like I'm talking to myself but hey ho

due to the reactivity of quicklime I'm not sure where to go about acquiringit or how to dispose of it.

Hot drink cans contain quicklime, maybe enough out of a few to experiment with? http://en.wikipedia.org/wiki/Self-heating_can You'd have to be carefull trying to extract it tho!

Oxyhydrogen is what you need for the temperature http://en.wikipedia.org/wiki/Oxyhydrogen it's not difficult to make but you do need dry gas to make the temperature you require.

 

[Paul Baldwin]

The first device I made, like I said, it's not exactly rocket science, pretty much anything works

You can see a ball of glass I "created" from a piece of smashed pint glass I was attempting to make a hole in. The nail was heated to cherry red before being bent very easily to the angle it is now and the can just oxidises if you get the flame anywhere near it!
When I renew the bubbler lid I'll have another go at heating some lime for a longer period and see what happens

 

[Paul Baldwin]

Maybe this text I just found will prompt a few more responses?

"Drummond said that the limelight is of a such dazzling whiteness that it is plainly visible sixty-eight miles away, and it is reported that a sharp shadow was cast at a distance of thirteen miles."
"This near 'point source' of light was found to be ideal, in conjunction with lenses, to make optical systems that were soon put to use in lighthouses and in the theatre (the first spot lights), hence, to be 'in the lime-light'."

That sounds like real candlepower! :candle::devil:

Found here http://www.chem.leeds.ac.uk/delights/texts/Demonstration_19.htm

Apparently chalk lime is the stuff you need for maximising the effect.

 

[bwrich]

I used an air-breathing propane torch and a piece of common white chalk, and, surprisingly, the heated end of the chalk DID luminesce! Chalk is Calcium Carbonate (CaCO3). When heated, molecules of Carbon Dioxide (CO2) are driven off, leaving only Calcium Oxide (CaO).

I have an 18 inch polished steel parabola. Someday I hope to create a strong "searchlight" beam using it and lime light.