"Don Foreman" wrote in message
...

Guy Lautard (a Canadian) addresses case -hardening in one (or more)
of his Bedside Readers. I think one method was using bone meal in a
"muffle" comprised of a piece of iron pipe. This could be done in a
charcoal fire.

Bone meal and barium carbonate (for, I think, color hardening). Barium
carbonate may be had fairly inexpensively from some ceramics shops, and from
most pyrotechnic chemicals dealers, like Skylighter.com and Firefox.com

LLoyd