1008 Wisconsin Academy of Sciences, Arts, and Letters. 
Methods for the Determination of Filix Acid. 
As the oleoresin was originally thought to owe its teniafuge 
properties to its filix acid content, the determination of this 
constituent naturally received consideration first. The nature 
of the methods devised for its estimation and their subsequent 
development is illustrated in the descriptions which follow: 
Method of Kremel (1887): Place a weighed quantity (about 10 grams) 
of the oleoresin in a flask and macerate it successively with several portions 
of petroleum ether when the greater part will be dissolved leaving the 
filix acid as an insoluble residue. Collect the latter on a fiilter and wash 
with more petroleum ether. Then dissolve it while on the filter in hot 
alcohol, remove the latter by evaporation and again wash with petroleum 
ether to remove the last traces of fat. Finally dry and weigh. 
Method of Bocchi (1896) :* Dissolve 1 to 2 grams of the oleoresin in a 
small quantity of ether, place the solution iu a separatory funnel and 
shake it with successive portions of lime water until the shakings become 
colorless and remain clear on the addition of acetic or hydrochloric acids. 
Filter the united lime water solutions into a separatory funnel and acidify 
with hydrochloric acid when a dirty yellow precipitate will form. Dis¬ 
solve / the latter by shaking with carbon disulphide added in successive 
portions, unite the shakings, filter and remove the solvent by evaporation 
on a water bath. Dry and weigh the residue which is pure filijx acid. 
Method of Kraft (1896): Add a solution composed of 2 grams of 
potassium carbonate, 40 grams of water and 60 grams of alcohol (95 per 
cent.) to 5 grams of the oleoresin in a suitable flask and shake for 15 
minutes. Filter 83 grams of this liquid into a separatory tunnel, add 9 
grams of dilute hydrochloric acid, 50 grams of ether and 35 grams of 
water and shake vigorously. After the mixture has separated draw off 
the lower hydro-alcoholic liquid and repeat the shaking, using 35 grams 
more of water. Separate the latter and run the remaining ethereal so¬ 
lution into a tared Erlenmeyer flask of 100 cubic centimeters capacity. 
Distill off the greater part of the ether and evaporate the remainder down 
to about 2 grams. Dissolve the dried mass in 1.5 grams of amyl alcohol 
and precipitate the filix acid by the addition of 30 cubic centimeters of 
methyl alcohol (5 cubic centimeters added at once and the remainder drop 
by drop.) Allow the precipitate and supernatant liquid to stand over 
night in a cool place, then collect the former on a tared filter and wash 
it with 15 cubic centimeters of methyl alcohol (use 3 portions of 5 cubic 
centimeters.) Finally, dry the precipitate at a temperature between 60° 
and 70°C and weigh. The weight obtained will represent the filix acid 
contained in 4 grams of the oleoresin. 
1 The procedure as outlined above really gives the amount of total acid 
substances (crude filicin) present, but is described here as it was proposed 
by its originator as a method for the determination of the filix acid content. 
