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JOURNAL OF FORESTRY 



These results also prove the fact that "black wood" surpasses ''red 

 wood" in the content of "particular substance," with the one exception 

 of No. 10, to which particular attention is to be paid, according to the 

 reason supplied later. 



(HI) To verify the fact that "particular substance" undergoes a 

 chemical change in this phenomenon, a thin board was prepared from 

 green "black wood" and exposed to ordinary conditions. Immediately 

 after the complete darkening of the surface, shavings were taken from 

 both outer and inner parts of the board and their infusions were tested 

 after the following duration of extraction. 



Table 4. 



This shows clearly the diminution of the content of "particular sub- 

 stance" in the outer part affected by the darkening. 



(IV) For the same purpose as (II), each of the 16 shavings pre- 

 pared from green "black wood" was cut into two pieces ; half piece 

 of each was subjected to rapid drying to avoid the extreme darkening, 

 keeping it moist. Small pieces of equal quantity were provided from 

 the contiguous parts of the original shavings as test materials. These 

 small pieces made six groups and three sets of colorimetric tests as 

 shown in the following table : 



Table 5. 



