6 



BULLETIN 508, U. S. DEPAKTMENT OF AGEICULTURE. 



In Bulletin 129 the averages for beech, birch, and maple included 

 yields from heartwood and lumber. Later experiments on tempera- 

 ture control have shown that in these experiments yields from lum- 

 ber were not strictly comparable with those from heartwood, and 



75 100 125 150 



PERCENTAGE 



Fig. 2.— Relative yields of wood alcohol per cord. (Average yield from heartwood of 

 beech, birch, and maple from Indiana and Wisconsin equals 100 per cent.) 



