1912-13.] The Absorption of Light by Inorganic Salts, No. X. 149 
of these ions, supposing that the part of the salt which is not separated 
into ions is itself colourless. . . . 
Fig. 1. 
“ Special relations are observed when the non-dissociated salt is itself 
coloured. For instance, anhydrous cupric chloride, or a solution of this 
salt in indifferent solvents (wherein it is not separated into ions), is coloured 
intensely yellowish brown. Therefore, a solution of this salt, which 
