451 



21. Furil. 



22. Benzfuril. 



23. Terephtalophenon. 



'/l6 

 (saturated) 



2.80 



Remark. After some time's illumi- 

 nation the absorption, which was 

 constant at first, descends to 0; in 

 this the ketone itself is attacked with 

 decoloration of the liquid 



24. Isophtalophenon. 



25. Phenanthrenequinone. 



Remark. Behaves like furil. 



26. Anthraquinone. 



0.004 



(saturated) 



0.6T 



27. Camphorquinone. The activity varies with the origin of the preparations. 



Some five varied at '/« mol. from 0.19-0.43. With still lower concentrations, 

 and also with very small ones the activity is practically not perceptible 



28. Fluorenone. In all concentrations — also very small ones — inactive. 



29. a-Hydrindon. 



Weekbl. 13, 594 (1916); it melts amidst decomposition at 116°— 124°. It is still 

 uncertain whether the structure formula is: 



QHs CeHs 



I I 



HO-C C-OH , 



I I 



c=o c=o 



I I 



CH3 CHs 



CH3 CH3 



I I 



HO C C-OH 



C=0 C=0 



I I 



CfiHs CgHj 



