956 Wisconsin Academy of Sciences . Arts, and Letters. 
constant in this connection in the literature until 1903. In that 
year, the English firm of Southall Brothers and Barclay pub¬ 
lished a statement in their Laboratory Reports , in which a stan¬ 
dard range for the specific gravity of the oleoresin of aspidum 
was given. Interest in the matter again seems to have waned 
and it was not until 1911, when Parry showed that the last 
named preparation was being extensively adulterated with castor 
oil, that the necessity for standardizing this preparation be¬ 
came apparent. The subject was then taken up in earnest, 
however, and in 1913, no less than four articles on the deter¬ 
mination of the physical and chemical constants of the oleo¬ 
resin of aspidium made their appearance. In each of these, 
the determination of the specific gravity was given some con¬ 
sideration. 
From the foregoing brief resume of the literature on this sub¬ 
ject, it becomes apparent that the determination of the specific 
gravity as a factor in evaluating the oleoresins has received 
consideration in connection with but two of the official prepara¬ 
tions. Furthermore, that practical use has been made of this 
constant only in the case of the oleoresin of aspidium. The 
results obtained with respect to these two preparations, how¬ 
ever, are deemed to be of sufficient importance to warrant the 
determination of this constant in the case of the other members 
of this class of preparations. 
The manner in which this constant was determined by the 
above mentionel investigators does not become apparent from 
their work as reported in the literature. It is thought, how¬ 
ever, that an ordinary glass pycnometer and chemical balance 
were employed for this purpose. In the determinations made 
in the laboratory, a 10 cubic centimeter pycnometer was used, 
except in the case of the oleoresin of lupulin which was usually 
too thick to handle in this manner. For the determination of 
the specific gravity of the latter, a Nicholson’s hydrometer was 
employed. All determinations were made at 25° C. 
The results as obtained in the laboratory and those reported 
elsewhere will be discussed in detail under the treatment of the 
individual oleoresins. 
Refractive index: 
The determination of the refractive index has received con¬ 
sideration only in connection with the standardization of the 
