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Transactions of the Uoyal Society of South Africa. 
These are combinations of the two former ideas, and depict phenol- 
phthalein both as benzaurine-derivative and as a phthalophenone. They 
explain the easy formation of an oxime, and the easy change of the latter 
into oxybenzoylbenzoic acid and para-aminophenol. 
I should add, of course, that I have no doubt that solid colourless 
phenolphthalein has the accepted lactone formula ; the only question that is 
in doubt is the constitution of its coloured solutions in alkali, and I am 
fairly confident that the latter do not contain a free — COoNa (or — CO2' ion), 
but are wholly phenolic in their character. The same applies to fluorescein, 
which may turn out to be merely an oxo-dioxyphthalophenone when in 
alkaline solution, although a triphenylcarbinol-derivative when solid. 
