958 Wisconsin Academy of Sciences , Arts, and Letters. 
nature of these preparations exclude the presence of any great 
quantity of moisture. This statement has been borne out by 
laboratory experiments. Attempts to determine the moisture 
by means of the xylene 1 ) method failed to reveal the presence 
of a measurable amount of water in any of the samples examined. 
The loss in weight is, therefore, due, ordinarily, to the removal 
of volatile oil and in exceptional cases to the removal of un¬ 
evaporated solvent. Such being the case, the determination of 
this constant serves as a means of measuring the amount of 
volatile oil naturally occurring in these preparations and as a 
means of detecting the presence of unevaporated solvent. 
The amount of weight lost by the oleoresins when deter¬ 
mined as stated above varies greatly with the individual 
members comprising this class of preparations. The oleoresin 
of cubeb which contains a comparatively large amount 
of volatile oil naturally sustains a comparatively great 
loss, while the oleoresin of capsicum which contains 
a small amount of volatile matter shows but a slight loss. 
There is noted a further variation in the case of each individual 
due to a variation in the amount of volatile matter naturally 
occurring in the drug from which the oleoresin was obtained, 
or to a variation in the conditions under which the individual 
was prepared. As an illustration, the oleoresin of cubeb may 
be cited. The volatile oil content of cubeb is stated to be 10 to 
18 per cent. A much greater variation is, therefore, to be ex¬ 
pected in the oleoresin which represents only the alcohol soluble 
portion of the drug. With respect to the conditions under 
which the oleoresin of cubeb is prepared, observations in the 
laboratory have shown that the preparation will contain a larger 
amount of volatile oil when the solvent is allowed to evaporate 
spontaneously at room temperature, than when the same is re¬ 
moved by evaporation on a water bath. In most cases, the 
variation, due to the difference in solvent used in extracting 
the oleoresins, appears to be so slight as to be almost negligible. 
In the case of the oleoresin of pepper, however, there is a very no¬ 
ticeable difference. This is very likley due to the nature of the 
preparation, its viscosity making it difficult to remove the last 
traces of the less volatile solvents without the application of 
heat. 
1 IJ. S. Dept. Agric., Forest Service, Circ. 134. 
