DERIVATIVES OF DIPHENOQUINONE. 



261 



barium salt forming lustrous prisms arranged in rosettes. Dried 

 over calcium chloride 0.1195 lost 0.0067 ^^ 150° ^^'^^ gave 0.0510 

 BaS04 



Found : H2O = 5.6%, Ba = 25.1%. 



OH _|. 2H2O requires UoO = 



■6.6, Ba = 25.2 9^?. 



This acid gives a bright blue coloration with ferric chloride 

 and a deep orange with chromium trioxide (oxidation to sul- 

 phonic acids of dicresoquinhydrone and dicresoquinone). 



H. Halochromism of the Diphenoquinone Series. 



The following table exhibits the halochromism to H.2 SO4 of 

 all the known derivatives of the coerulignone family. 



* Almost opaque even in sunlight. 



f This is an extraordinary anomaly, as the formation of a quinonoid oxonium 

 salt is excluded : it is not due to an impurity, and the HCl oxonium salt is white, 

 I The author has been unable to make this substance. 



