On April 15, 2020 at 4:37 PM David Soderblom <drs@...> wrote:

A lot of coal was shipped fairly finely divided, in small pieces, large chunks with air gaps less so.  A reference book I have quotes the density of coal as 75 to 94 lbs/ft^3, so you could use the lower number.

David Soderblom

Baltimore MD USA

drs@...