Re: Marble Coals
I've been thinking and re-reading everything and I think some here are getting careless and might get hurt. Basically, my understanding is that the original poster was talking about marbles made of stone rather then glass. Stones are much better at retaining heat then glass so it seems that if you want to get a decent heat source it would have to be stone. Now I know a little about heating stones as some old fashioned ale recipes have you raise the temperature of the wort ( the sweet liquid you have prior to fementation ) by heating stones in fire and placing them into the liquid. The sort of stones you need are solid, no splits or cracks nothing porous as those kind of stones will explode.
How safe is it to heat stones for what we are talking about doing I can't say. Still, the idea is fascinating.