(517) 
If 5 ee. of fermentation liquid, or 5 e.e. of a liquid obtained by the 
action of indimulsin on solution of indican are placed in a stoppered 
eylinder mixed with 50 e.e. of the crude chlorophyll?) and a little am- 
monia and then well shaken, it will be found that not a trace of 
indigo-blue is formed. By agitating with ether the chlorophyll may 
be separeted from the aqueous layer, both portions may then be 
filtered and the filter examined for indigo. If, however, the experi: 
ment is made by first adding the ammonia and thoroughly shaking 
to promote oxidation, the addition of the chlorophyll solution will 
not prevent the formation of indigo-blue. 
8. I also found that both in acid and alkaline solutions the sub- 
stance yields red resinous products unless the air is excluded. 
All these reactions are typical indoxyl-reactions. To make more 
sure, I prepared indoxyl according to the easy and elegant process 
of HEUMANN and BACHOFEN. *) 
It was then shown that the solution of this indoxyl gave all the 
reactions mentioned in 1—S8 particularly the chlorophyll test. A 
fairly pure aqueous solution of indoxyl may, of course, be made by 
agitating the acid solution with ether, evaporating the same in a 
current of cold air and dissolving the residue in water. 
What struck me during the preparation is the difficulty of obtai- 
ning a solution of indoxyl which does not yield indigo when exposed 
to the air unless it had an alkaline reaction. Even when starting 
from indigo purified by sublimation this seemed impossible. I could 
not ascertain for certain whether indoxyl has the property of gra- 
dually forming indigo in acid solutions, or whether this formation 
is due to any impurities. But even if it should not be a property 
of indoxyl itself, the formation of indigo in the fermentation fluid 
necd not cause any surprise, as this is a very impure solution of 
indoxyl and, as will be seen, its reaction is much altered during 
the oxidation. °) 
From the foregoing it may be concluded with certainty that in 
') When using this expression, I do not, of course, mean to say that chlorophyll 
itself exercises the said action, 
2) Ber. d. D. Chem. Gesell. 26. p. 225. 
%) The following interesting phenomenon may be mentioned to show the influence 
of the dissolved substances. If sulphuric acid is added to a solution of indoxyl 
until the liquid turns red, scarcely any indigo will be formed on shaking. If however, 
an excess of Na,HPO, is added indigo will be formed. Still, the amount of Na,HPO, 
may be easily regulated so as to leave the liquid acid. It is also interesting to know 
that the liquid containing Na,HPO, does not immediately give the isatinsoda reaction. 
