244 SEMI-CENTENNIAL OF TORREY BOTANICAL CLUB 
which must elapse in the many filterings and extractions may 
allow a chance for partial disorganization of the unstabler acids. 
These considerations have influenced the writer in his own 
work to sacrifice the clearness of the solution to be titrated 
for rapidity of estimation. It is true that from the standpoint of 
the chemist the extracts procured are often cloudy and colored 
so that the end point is not so sharp as it would be in a clearer 
solution but by the use of rather greater quantities of the indicator 
than usual and by accustoming the eye to the behavior of the 
specific plant juice it is probable that the results obtained are 
more nearly accurate than by a method which in the chemical 
sense may be more perfect. I am fully aware of the various 
objections which the chemist may bring to the procedures as 
outlined, and I admit their inadequacies. For the purposes de- 
sired, however, they are more suitable than more elaborate ones. 
The two greatest difficulties are, first in the color of the 
solutions and second in the precipitation of protein substances 
when the neutrality point is approached. For the first there is 
at present no very good remedy to be suggested. By the selection 
of an indicator the color change of which is compatible with 
observation in an already colored solution, something may 
done. The color change of the juice often suggests itself as an 
indicator and if one were certain of the neutrality of its end point 
it could be used instead of an indicator. As to the flocculation 
of colloidal substances on the approach of the neutral point it 
may be said that the precipitate is usually white and does not 
interfere as much with the color reaction as.might be supposed. 
Of course in separating out the protein may adsorb some acid, 
but since the precipitate does not appear until the solution is 
nearly neutral the amount so occluded cannot be large. The addi- 
tion of substances like bone-black for clearing and decolorization 
is tempting but open to various objections, the most important 
of which is that the bone-black may itself adsorb acids. 
The writer would welcome the suggestion of improvements in 
the procedures outlined, particularly in the matter of a satis- 
factory method of obtaining a perfectly clear and colorless extract 
for titration purposes. It so happens that the plants which I have 
especially been investigating yield juices which are usually fairly 
