In the light of definition of compressibility of matter and fractal descrip
tion of coal pore volume, a calculating formula on pore compressibility of
coal (beta(P)) has been obtained, and that beta(P) and beta(S) (compressibi
lity of coal matter) decrease with the increase of experimental pressure, a
nd they are relative to sampling sites of coals. (C) 1999 Elsevier Science
B.V. All rights reserved.