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Transactions of the Boy at Society of South Africa. 
in which only the tautomeric double-bonds are written. This consists of 
two of the phenol- or para-oxjphenyl-rings, joined by a middle tautomerism: 
The calculated wave-length is therefore 2 x 219 + 103 = 541. The observed X 
was about 539 (own observation). 
(2) Benzavrine in alkali {aqueous). 
This is the phenyl-derivative of the foregoing, with CPli in the middle 
instead of OH. As this is a middle loading, the value is 14 to 16 according 
to the size of the group. Taking 16 for phenyl, the calculated value for 
benzaurine is 541 + 16 = 557. The observed X was 553. The other two 
bands at XX 370 and 290 are, in my opinion, due to shorter tautomerism s 
of three and two units respectively. 
(3) Diamiiiohenzhydrol (neutral chloride in vmter). 
The formula is 
and consists of two para-aminophenyl-rings united by the tautomerism CCC. 
The calculated wave-length is therefore 2 x 223 + 103 = 549. I have observed 
in a crude product X 548. Watson (l. c, p. 88) gives X 564 in alcohol. It is 
to be noted that in alcoholic solution such dyes are not ionised, i. e. are 
loaded with chlorine on the nitrogen, and therefore give a higher wave-length 
than in water. 
(4) Boehners violet in water. 
This is the C-phenyl-derivative of the foi-egoing, related to No. 3 as 
No. 2 is to No. 1. The calculated wave-length is therefore 16 more than 
549, or 565. The observed X was 562. Meyer and Fischer (Berichte, 1913) 
give X 570 in alcohol, with two lower bands at XX 400 and 300 due to shorter 
tautomerisms. 
(5) Michlers hydrol in water. 
The formula is as in Fig. 1. The calculated colour is 2 x (Me.^NCC) + 
CCC or 2 X 251 + 103 = 605. Observed in water X 602, in alcohol X 610. 
(6) Malachite-green in water. 
This is the C-phenyl-derivative of Michler's hydrol (Watson, /. c, p. 90); 
hence its calculated wave-length is 16 + 605 = 621. Observed X 619 in 
water. 
(7) Sodium phenate and (8) aniline. 
This is an example of a simple triple tautomerism in which the whole 
benzene-ring takes part : 
CH = C: 
CH-CHV • . 
...... ^n_f 
;C-b/ (or NH,). 
CH = CH' 
