1010 Wisconsin Academy of Sciences , Arts, and Letters. 
residue in 1 cubic centimeter of amyl alcohol, and, after the solution has 
stood in a cool place for 48 hours, add 15 cubic centimeters of methyl 
alcohol. After standing for 24 hours more, collect the precipitated filix 
acid on a filter, wash with 5 cubic centimeters of methyl alcohol, dry on 
a water bath and weigh. 
It will be noticed that the preceding methods, with the ex¬ 
ception of the one devised by Kremel, are very similar in gen¬ 
eral outline, practically the only difference being found in the 
procedure by which the crude filix acid is directed to be purified. 
This difference is of special importance, however, as the weight 
of the product finally obtained will naturally vary with the de¬ 
gree to which purification has been effected, and this in turn 
will cause the computed percentage to vary, as is shown in the 
following table: 
Table 27.— Variation in filix acid content due to the difference in the meth¬ 
ods employed in its determination. 
Date 
Observer 
Per cent, of filix acid by the method of 
Bocchi 
Kraft 
Fromme 
(Original) 
Fromme 
(Improved) 
1897 
1897 
1897 
1898 
Gehe & Co. 
13.24 to 30.85 
3.28 to 11.32 
13.07 
6.58 
6.00 
Madsen. 
12.10 
5.85 
5.20 
Plzak ..... 
6.48 
The above table shows further that the filix acid is obtained 
in the state of greatest purity when the improved method of 
Fromme is employed. And this method was usually given 
preference in the valuation of the oleoresin until it was dis¬ 
covered that the teniafuge properties were not due to the filix 
acid, alone, but were to be attributed in part to the presence of 
a number of other substances as well, compounds resembling 
acids to a certain extent in their chemical behavior. 
Methods for the determination of the Crude Filicin. 
With the above mentioned advance in our knowledge con¬ 
cerning the therapeutic constituents of -this preparation, the 
methods for the determination of the filix acid lost their value 
and have since been superceded by those which have for their 
