Comments by Lloyd Bogart (and Bert Kamphuis)
I read your WWW page with interest and not a few chuckles!
Then again, cooking does not require boiling, per se, and cooking at a heat just below boiling might reduce evaporative loses of heat,
as would some sort of covering.
Still to be determined, I suppose, is how well water might be brought to boil by adding heated stones to your suspended pot of *preheated*
water, and whether the boil could then be *maintained* for a period of time, without lowering the pot into the flames. A stout suspension
system would be a must, or pot, rocks, ET AL would soon be in the flames.
All in all, your experiments were quite creative and entertaining.
Do you think that pre-shrinking the pot, by boiling it, might produce a container of greater dimensional stability? (It might also reduce the
rawhide flavoring of the material cooked later.) I'd think that partially filling it with sand would prevent it's taking on an unwanted shape.
A similar boiling technique was used in making leather body armor, where shape was an important consideration.
But that brings up a nasty question: what would the cave bear folks have used as a container for boiling and shaping their new pots? The mind
balks at the prospect of an endless recursion of the chicken and egg variety, and so I'll leave it to you to post an update. :-)
Looking forward to it;
I just read your enjoyable account of your experiments with the leather cooking pot. I will give you some of my ideas on this subject
I always saw this pot as a supported pot, not a self supporting one. That means with a frame on the inside, made of wood (fairly sturdy pieces) or bone.
This would then avoid shrinkage of the pot.
[I have to disagree with Bert here. Shrinkage over the fire is dramatic, beyond the scale of the shrinkage which occurs with soaking and simply drying.
I suspect the either the inner frame or the skin would give under the tension. Also once shrinkage has occurred the pot will keep its shape even with
liquid in it over fire. The preshrinking over fire with sand method described by Lloyd Bogart (see message above) would be a good way to avoid deformation. ~ EP]
In heating something the rate of heat input has to exceed the rate of heat removal. A good way to test this is to measure the temperature as a function of time with a
thermometer. This way you can asses whether the water is still getting hotter, or whether equilibrium has been reached.
Heat transfer into the water can be improved by using thinner leather, and, because of the better heat removal from the outside of the leather, charring can be avoided
(perhaps completely). Another added effect is that this way the diffusion of water to the outside of the leather is improved, so that it will char even less. I think wet
leather should be capable of withstanding up to 250 Celcius.
The flames: I don't know what kind of fire you used, but I would select a fire with big yellow flames. These are not very hot you see, not as hot by far as the red/white
glowing parts of the fire.
Overall, from an engineer's point of view, you want to:
Select your fire and the height of the pot above it to protect your leather.
Ensure good heat transfer into the water by using thin leather.
Reduce the heat loss by reducing the size of the liquid surface open to the air. That means a narrow, deep pot, or even an 'amphora' shaped pot with a narrow neck.
My gut feeling says that it should be possible, because it is possible to heat water to boiling in a paper container.