Today was the last full day of experimenting and these are the results after a 6.5 hour continuous burn.
Beginning weight of coal 57#
Beginning volume of coal 1 bushel
Ending weight 3.5#
Total Coal Burned 53.5#
Final ash weight 5.35# / 10% by weight
Final ash volume .23 bushel / 23% of original volume
Note: The ash was not compacted in any way.
There was no unburned coal and no large clinker. No clinker any larger than 2 inches; exactly the same as anthracite clinker.
There was concern voiced about clinkers not falling off the edge. I tried to video but after radiation burns, I decided to take pictures at half hour intervals and one video of a large clinker falling off.
Note the clinker in the back right corner and front left corner.

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Half hour later, the rear right clinker had fallen off and the front left clinker is growing.

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Half hour later, the front left clinker was ready to fall off and I took this video. The ash falls off from the middle to the end of the video.
http://www.youtube.com/watch?v=D0a0B1nqsLwThis is the pot with the clinker gone.