Colour and Chemical Constitution. 
39 
an ionisable group, always co-operate : consequently the electron- orbit is very 
much larger and the colours much higher. Part X of this work might 
therefore be re-written without the hypothesis of fuchsene by making 
dioxybenzhyclrol the parent-substance, whereby on using the dicyclic colour- 
factors given in Part X, all the colours are calculated without exception, 
because the exceptions given there are all monocyclic. As an example, 
dioxybenzhvdrol 
HO — ; 
— CH-OH— < 
"\. 
of A 539 in alkali can be treated with the dicyclic factor 1-059 for NMe 2 /OH 
to give Michler's hydrol (factor applied twice), and so on. This is elaborated 
in Part XIY. 
