Calcination
I entered the realm of alchemy when I tossed the chicken and lamb bones into the hot coals in the Weber grill on Friday night. First there was a huge amount of flame as the meat and fat burned off. We stood back and watched (so did one of our neighbors). "That a lot of calories," Tod commented.
Heating the bones
After the fire settled down, we watched the bones turn from charred black to white as they heated up and burned away everything but their calcium. This is called calcination. It's one of the 12 vital processes alchemists used to transmute substances.
Calcium shells of chicken and lamb
After about half an hour or so, the bones were "whiter than ash" and I drew them from the fire. They were lightweight, brittle and chalky. They cooled very quickly; when I photographed them less than five minutes after taking them out of the coals, they were room temperature.
I can understand why alchemists were impressed with calcination.