188 
Transactions of the Royal Society of South Africa. 
Some General Quantitative Conclusions on the Effect of Substitutions 
on Phenolphthalein. 
C/~ llldjll Y -I- gi^JLlij 1 dixoCyo a/KJij\J± iJVlyJA-X 
wave-length by 1"5 per cent. 
JL W W ^± \J LLlJiJ lailioXD 
2-9 
One m-methyl group raises 
2-7 
5> 
Two „ groups raise „ 
„ 5-5 
One o-isopropyl group raises 
„ 1-3 
„ (?) 
Two groups raise ,, 
„ 2-4 
>> 
One m-isopropyl group raises 
„ 3-0 
Two „ groups raise „ 
„ 5-6 
Replacement of phthalic CO by 
SO2 raises „ 
„ 1-4 
Two o-Br atoms raise „ 
„ 1-7 
Four „ „ „ „ 
„ 5-0 
Four 0-1 „ „ 
„ 6-0 
The oxygen " 0x0 "-linkage in 
fluorescein depresses „ 
„ 10-0 
There are many other additive relationships which are, however, less 
regular than these, possibly owing to difficulties of observation only. 
