Instead of doing my scale over, here is what Coal kirk did, his post is copied below. Its seems to validate my rice coal weight per cu ft. More hard data is better.
coalkirk On: Mon Sep 15, 2008 7:57 am
i took a 5 gal. bucket of rice coal to my dogs vet office where they have a digital scale. It was 38+ lbs.
CoalKirk's data does not state if he subtracted the pail weight which I measured as 2.5 lbs on my scale. This 2.5 # sounds reasonable even without a scale. This suggests the coal alone weights 38 -2.5 or 35.5 #'s.
Here are my calcs:
1 gal liq = 231 cubic inches, so in 5 gallons there is 5 x 231 = 1155 cu in. A cu ft is 12 x 12 x12 = 1728 cu inches, so doing the proportion, 35.5 lbs /X = 1155/1728 and solving for X, X = 53.1 lbs per cubic foot. This is darn close to my 52.5, though I trust CoalKirk's scale more than mine.
If Coal assumed the 38 lb # in a 5 gal pail was only the coal, a cu ft of his rice coal then weights 56.8 #'s/cu ft based on the same type calculations as above. I'm of some though he originally did not minus the pail weight.
It's important to be aware that different coal sizes have more or less air gaps between them in a pail, this influences the density assessment. Plus antracite density does vary a bit.
I guess based on Coal Kirk's #'s backing me up, I'm pretty much still standing by my original #'s unless we get more hard data.