HEARTWOOD OF CRYTOMERIA JAPONICA 849 



substance contained exclusively in all the heart wood of "Sugi," a 

 substance which is easily soluble in water and gives very marked red 

 or purplish red color with alkali, qualitative tests of tannin or gallic 

 acid were not applicable to the infusions. Potassium cyanide gave a. 

 red color to the infusions, but the color was quite steady and not like 

 that produced by tannin which disappears and ma}- be brought back 

 by shaking. Tests of wood extracts at several different stages of 

 conversion gave confirmatory results. No trace of iron was observed, 

 m these infusions, and we were unable to produce the dark color of 

 "black wood" by darkening the wood artificially with ferric chloride 

 and ferrous sulphate. 



These experiments show that water-soluble tannin or ferrous com- 

 pounds do not come into play and radically deny the chemical 

 hypothesis. 



PARTICUI.AR SUBSTANCE CONTAINED IN THE HEARTWOOD OF "SUGl" 



It is of seeming significance that this kind of darkening of the 

 lieartwood is peculiar to "Sugi" as far as Japanese trees are concerned, 

 and that this particular substance is limited to the heartwood of "Sugi." 

 A few years ago the present writer conducted a series of experiments 

 with wood shavings to test the reaction with alkali in regard to the 

 fluorescence of wood infusions.'' The color of the infusions from 

 fresh "red wood" was mostly reddish and that of well dried materials 

 faint red, while the old air-dried materials gave generally faint yellow 

 or colorless infusions. But all these infusions turned to distinct red 

 or purplish red with alkali and no parallel to this was then found 

 among the infusions of other Japanese woods, although some tropical 

 woods came later to the writer's notice as somewhat comparable.^ 

 On the other hand, the infusion from such grayish brown materials as 

 completely culminated in the conversion of tint was entirely devoid of 

 this marked color reaction. 



These experiments and the fact that shavings from fresh "black 

 y/ood" can be freed from the darkening after slight extraction with 

 water, favor the view that the "particular substance" in question is 

 at least one of the factors largely responsible for the phenomenon. 



' Fujioka, M. On the Fluorescence of the Infusion of Woods. Bulletin of 

 the Forest Experiment Station, No. 15. 1914, pp. 46-G4 (in Japanese). 



''Fujioka, AI. Fluorescence of the Infusion of the Woods of South Sea 

 Islands. Bulletin of the Forest Experiment Station, No. 21, 1920, pp. 89-103. 



