Abstract: This paper comparatively analyzed ash contents, extractives, cellulose, lignin and etc., in total nine chemical components from epicarps of hickory, chestnut, and sasanqua to pine sawdusts and fir sawdusts, which are normal materials for machine-made charcoal briquettes. The conclusions are:the hickory epicarp is constrained in massive production of machine-made charcoal as a substitute of sawdust due to too much ash content(12.23%);the amont of extractives from the hickory epicarp and the chestnut epicarp, extrated by means of cold water extracting, hot water extracting, and 1% NaOH extracting separately, are all higher than that from pine sawdusts and fir sawdusts, which illustrates the epicarp contents more low-molecular pentosan and low-molecular lignin than that of pine and fir dust that the former is limited to replace the latter in producing machine-made charcoal in great number.

Key words: epicarp, chemical composition, raw material