Colour and Chemical Constitution. 
67 
(5) Doebner's violet. — This is No. 4 less four methyl groups. Calculated 
A = 1400 (see 15 lines above) x 0-39 x 1-026 = A 561. Observed X 562. 
(6) Aurine. — Here the linkage K is used instead of linkage E, although 
they are nearly the same. As shown in Part XII, p. 209, only two of the three 
rings act in producing the colour. The calculated A is 1380 x 0 386 = X 533. 
Observed X 534. 
(7) Fuchsine (para). — Two aniline rings and the factor K are used. 
Calculated X = 1400 x 0 386 = X 541 . Observed X 543. Commercial fuchsine 
has an extra C-methyl group and has X 549. Calculated, using the C-methyl 
factor 1 012 = X 547. 
(8) Crystal violet. — Two dimethylaniline rings and factor K to be used. 
Calculated 1548 x 0-386 = X 597. Observed X 595. 
(9) Aniline bhie. — Two diphenylamine groups and the factor K to be 
used. The JST-phenyl factor has twice the effect of the C-phenyl factor 
(cf. ortho- and meta- groups in Part IV, p. 188). Its value is therefore 
(1 026) 2 = 1 054. Hence two diphenylamine groups have the value A 1400 
X (1 054) 2 = A 1554, and the calculated value for aniline blue is 1554 x 0 386 
= A 599. Observed A 600. 
(10) Phenolphthalehi. — This is No. 1 with a benzoic acid group attached. 
The factor for the latter is C-phenyl multiplied by o-carboxyl (see Part X, 
p. 306) = 1 026 x 1 002 = 1-028. Calculated A for phenolphthalein = 1380 
X 0-39 x 1 028 = A 553. Observed A 554. 
(11) Phenolsu Ipho nephthalein. — This is No. 1 plus a benzenesulphonic 
acid group. The latter's factor is 1 026 x 1 018 (Part X, p. 308) = 1 045. 
The calculated A is 1380 x 0 39 x 1 045 = A 562. Observed A 563. 
(12) Michlers ketone. — Two dimethylaniline rings and the factor F are to 
be used. Calculated A 1548 x 0 234 = A 362. Observed A 364. 
(13) Indophenol. — This is the anhydride of dioxy-diphenylhydroxylamine. # 
Two phenol rings and the factor G are therefore to be used. Calculated 
A = 1380 x 0 47 = A 649. Observed A 650. 
(14) Indamine. — This in the same way is derived from two aniline rings 
and the factor Gr. Calculated A = 1400 x 0 47 = A 658. Observed A 660. 
(15) Bindschedlers green. — This is tetramethylindamine, and the calcula- 
tion requires two dimethylaniline rings and the factor G — X 1548 x 0'47 
= A 728. Observed A 730. 
Doubly-linked Dicyclic Colours. 
Of these there is an enormous number in use, varying from eosine to 
safranine and methylene-blue. If all the ten factors were used two at a 
time there would be 100 colours of each of the three classes, viz. phenols, 
anilines and dimethylanilines. I therefore limit myself to those I have 
observed, or for which data exist in the literature. 
* Commercial "indophenol" is a naphthol compound. 
