18 
Schaer made use of it as a reagent for the oxidases, however, I have 
been unable to determine from an examination of the literature at pres- 
ent accessible. It therefore occurred to me that this substance micht 
c 
prove to be a very beautiful and delicate reagent for the oxidases. 
With the view of testing the conduct of aloin toward the oxidases, 
the following solutions of this substance have been prepared: 
Alcoholic aloin . — This solution was prepared by dissolving 0.25 to 
0.5 grams of powdered aloin in 50 cc. of 95 per cent alcohol. In some 
of our observations this solution was made use of without further 
treatment or modification. Generally, however, it was shaken with a 
small amount of zinc dust and filtered, inasmuch as it was found that 
such treatment considerably increased the sensitiveness and delicacy 
of the reagent. A solution of powdered aloin in a 10 per cent aqueous 
solution of chloral hydrate has also been employed, and in all cases 
these two solutions have been employed side by side with alcoholic 
guaiacum by way of comparison. In carrying out the tests. 2 or 3 cc. 
of an aqueous solution or extract of the material to be tested was 
brought together with from 0.1 to 1 cc. of the reagent, and the color 
change, if any. noted. Among others, the following plants have been 
examined both with aloin and guaiacum: 
Color produced with reagent. 
Name of plant. 
Part examined. 
Guaiacum. 
Alcoholic 
aloin. 
10 per cent 
chloral aloin. 
Potato, Solarium tuberosum. 
Tuber 
Deep blue . 
Deep wine 
red. 
Deep wine 
red. 
Eggplant, Solarium melon- 
Fruit 
do 
do 
Do. 
gena. 
Sweet potato. Ipomcea ba- 
Tuber 
do 
do 
Do. 
tatas. 
Dandelion, Taraxacum offi- 
Leaves 
do .... 
do 
Do. 
cinale. 
Lactarius piperatus 
Whole fungus. . 
Very dark 
blue. 
Wine red . . 
Wine red. 
Lactarius volumen 
do 
Deep blue. . 
do 
Do. 
Lactarius indigo 
do 
do 
Deep wine 
red. 
Deep wine 
red. 
Still other fungi, as vet not certainlv identified, have also given 
excellent tests for oxidases both with guaiacum and aloin. It will be 
observed therefore that the parallelism between the guaiacum and aloin 
reactions is complete. Without entering further into details, it may 
be said that so far as the delieacv of the reagent is concerned guaiacum 
and aloin are very nearly equal. Toward the oxidases of certain 
plants guaiacum seems to be a trifle more sensitive than aloin. whereas 
with others the converse is true. However, there are certain advan- 
tages attaching to aloin as a reagent for the oxidases which put it 
ahead of guaiacum. In the first place, the red coloring matter produced 
