66 The Philippine Journal of Science im 



was then distilled off in an open vessel on the steam bath, and 

 the last portions allowed to evaporate in a vacuum dessicator or 

 in the air at room temperature. Usually the heavy, dark red 

 needles of the potassium salt crystallized out on standing. This 

 crystallization could often be hastened by the addition of a few 

 crystals of the salt. The free hydroxyquinone was then obtained 

 from the salt by very carefully adding dilute sulphuric acid to 

 the aqueous solution of the salt and extracting with ether. 



The quinone was obtained as a deep straw-yellow compound, 

 decomposing without melting, very easily soluble in alcohol and 

 alkalies, and readily turning brown on exposure to light. 



The color of the alcoholic solution is due to general absorption 

 in the red-color region, there being no color band, but a very 

 rapid increase in general absorption from 1/A=2,100 to 1/A= 

 3,200, with faint evidence of an incipient band heading at 

 approximately 1/A=2,400. Selective absorption is shown by the 

 compound in the ultra-violet region with a band at 1/A=3,580. 



The potassium salt has caused a broadening of the incipient 

 band of the quinone at 1/A=2,400 into a color band heading at 

 1/A=2,030. The second band is still present, although slightly 

 shifted toward the red, heading now at 1/A=3,450. 



CHLORANIL 







CI 



Cl- 



-/\_ 



\X 



-CI 



-CI 







Kahlbaum's chemically pure chloranil was recrystallized from 

 glacial acetic acid and afterward photographed in this solvent. 

 The olive-colored solution showed general absorption in the 

 visible region, with a band appearing near, namely at 1/A=2,725, 

 and a much deeper band in the ultra-violet region heading at 

 1/A=3,520. 



p-DICHLORDIETHOXYQUINONE 







-|-^-OC2H5 



CI 



HsCaO-l^^'-Cl 



II 

 



