10 
Transactions of the Royal Society of South Africa. 
Table II. 
Spectra of Derivatives of Fhioresceine (2-2' -oxo-j^henolphthalein) . 
No. 
Name. 
1 
Source. 
Centre of 
Absorp- 
tion 
Ba-nd. A, 
Frequency. 
1 

Fluoresceine 
PA and re- 
499 

20-05 
sorcinol 
2 
3-oxyfluoresceine 
3-oxy PA 
489 
20-45 
and resor- 
cinol 
3 
Qninolphthalein . 
PA and 
493 
20-25 
■ quinol 
4 
Phloroglucin- 
PA and phlo- 
497 
20-15 
phthalein 
roglucinol 
5 
E-esorcinben- 
Benzoic acid 
501 
19-95 
zeine 
and resor- 
cinol 
o 
Iso-GOsinG 
1 sir and le- 
503 
sorcinol 
7 
Succinyl resor- 
Succinic acid 
504 
19-85 
ceine 
and resor- 
cinol 
8 
Eosine (tetra- 
516 
19-35 
bromofluores- 
cein) 
9 
Erythrosine (te- 
525 
19-05 
triodofliTores- 
cein) 
10 
Galleine (pyro- 
About 
g-ailolpbtha- 
543 
lein) 
11 
Diethylrhoda- 
553 
18-10 
mine (neutral) 
12 
Diethylrhoda- 
540 and 
17-90 and 
mine in acid 
559 
18-50 
13 
Galleine (NaOH) 
560 
17-85 
broad 
Diminu- ^ „ 
tmn nf 1 CaUSB of 
Frequency.' D-inution. 
-0-40 
-0-20 
-0-10 
0-10 
015 
0-20 
0- 70 
1- 00 
Increase due to 
3-oxy group in 
phthalic ring. 
Increase due to 
moving of two 
OH from p tow- 
Constitution un- 
known. 
Loss of phthalic 
-CO-^Na. 
Addition of four 
Br in phthalic 
ring. 
Replacement of 
/"\ 
\ 
-CHo-CHg-COaH 
4 Br (ortiio) in 
phenol rings. 
4 I (ortho) in 
phenol rings. 
C02Hby 
— I ? Four - OH 
I groups. 
1- 95 Two -OH re- 
placed by two 
NEto groups. 
1-55 and Replacement by 
2- 15 NHEto ion and 
by NHEtoCl. 
About ? Four - ONa 
2 2 : groups. 
tives of phenolphthaleiii, and Table II gives those which possess the 
fluorane-oxygen linkage. As will be seen from column 4, the alkaline 
colours of these phthaleins cover every possible shade due to absorption of 
light, from the centre of the spectrum to the infra-red, which, from the 
practical point of view, is very important, since the order of eflRciency of the 
different substituents is probably the same for many other classes of dyes, 
from which the colour of many unknown dyes could be predicted ; at all 
