I don't have a thermometer on my kiln so I needed to find out what 825 C "looks like". The glowing bar is silver and it melts at little over 900 C. I know that if I leave the silver in for a while longer it will melt and so that the temperature is high enough for the calcination
I had to do this several times. This is a picture of the first go. In the later ones I put the Chalk right under the flame to get it hot enough, but the pictures don't look as cool as this. Oh. And unless you know what you are doing... don't do this at home.
I need to let it cool down well. I noticed that the chalk appeared whiter than it did before the clacination.
Here we go. Its not the bext quality footage, but notice the steam rising from the pot and that I am not wearing gloves (I probably should..) whilst holding it. They use chemical reactions like the one here in those single use finger and toewarmer packs you can buy at camping shops.
Slaked lime, or quicklime
This is the stuff that gets put on walls when limewashing. Its also been used to cover plague victims corpses in the middle ages (very well done for people who where not aware of the practise desinfecting) and in naval warfare according to wikipedia.
the wet mixture goes back into the furnace to get rid of the water. Note, start with a low temperature and then gradually lift it up, otherwise it can spark and explode as the steam escapes from under the already dried top.
Back to calcium oxide
Dry. Even as the picture was taken the top layers of the chemical where grapping carbon dioxide of the air and reverting back to the chalk I started with.
Jellybean of Thark4
Abe the Lion Tamer4