164 
Transactions of the Royal Society of South Africa. 
Substitution- products of Resorcin-benzeine. 
a- or c-oxy- 
6-oxy- 
^-methoxy- 
d- or m-oxy- 
{494 neutral 
492 alkaline 
484 neutral 
492 just alkaline 
544 alkaline 
493 
430+492 
498 
d- or m-sulphonic acid \ 
" resorcin sulphophthalein " J 
/^-tetrabromo-m-sulphonic acid . 527 
b-bromo- 
a- or c-bromo- 
a- or c-bromo-6-oxy- 
d- or m-bromo- 
b-nitro- 
/^-tetrabromo- . 
/^-tetrabromo-b-nitro- 
b-nitro-d- or ra-sulphonic acid 
. 493 
. 497 
f 490 neutral 
\^550 alkaline 
505 
500 
519 
527 
506 
It is to be noted that the list is limited from the fact that sulphuric 
acid cannot be used as condensing agent in making derivatives of resorcin- 
benzeine, because at an elevated temperature resorcin itself condenses to 
a coloured fluorescent compound " resorcin-ether," the nature of which 
is at present unknown. It has a dirty rose colour in alkali with AA 490 and 
550 and a bluish-green fluorescence. Phosphorus oxychloride, if not over- 
heated, forms a suitable condensing agent. 
The conclusions to be drawn in the case of resorcin-benzeine are : — 
A. The /, g, j, and k colour-factors are the same as those of phenol- 
phthalein and fluorescein, viz. about 1-0135 on the average for bromine 
taken as standard. Further experiment is necessary to decide whether 
the (/-factor is greater than the /-factor, and whether the g- and ^'-factors 
are identical, as they should be by symmetry. 
B. In the phenyl ring the effect diminishes in the order d, c, b, but in 
this case the effect is still positive at b, although it appears to be nil in 
fluorescein and is sometimes negative in benzaurine. Much further work 
is necessary to clear up these small anomalies. 
Addendum, 12th June 1922. — Professor G-. T. Morgan kindly sent me a 
sufficient specimen of 1-3-dioxynaphthalene to enable naphthofluorescein 
to be made and examined. It has AA 535 and 496. The ortho-meta 
naphthol/phenol factor is thus 1-042 in the dicyclic series. This could not 
be ascertained from naphtholphthalein, because the latter is a diortho- 
compound and therefore cannot be compared with phenolphthalein. This 
naphthalene factor can be employed to calculate the naphthosafranines 
and naphthacridines. 
The effect of the naphthalene ring in the dicyclic series is practically the 
same as that of two bromine atoms substituted in the gh or ij positions : 
i.e. the outer carbons of the naphthalene ring have almost no effect. This 
is of great theoretical importance. 
