INSECT POWDER. 77 



Procedure 1. 



For further separation of the materials present in this residue, the 

 entire material extracted by the petroleum ether was saponified by 

 boiling with alcoholic potash (22 grams of potassium hydroxid and 600 

 cc. 95 per cent alcohol to 32 grams of extract). The boiling was con- 

 tinued for 75 minutes, the alcohol removed by evaporation on the 

 steam bath, the residue taken up in water, and the alkaline solution 

 extracted with ether. The ethereal extracts, which were of a beautiful 

 reddish-yellow color, were combined, washed with a little water, 

 dried over calcium chlorid, and the ether removed by evaporation at 

 room temperature in a current of air. A mass of reddish-yellow 

 powder was left. On recrystallizing this powder from alcohol, the 

 first recrystallization removed all of the red color, and the second all 

 but a trace of the yellow color, leaving crystals of a very pale yellow. 

 The melting point of these crystals (167° to 168°) and tests for a 

 phytosterol showed it to be a phytosterol-like substance. Tested 

 upon insects (roaches, ants, and aphides), it proved to be inert. 



The mother liquors from the recrystallizations were evaporated to 

 dryness in a vacuum desiccator over sulphuric acid. More of the 

 phytosterol-like substance was obtained, but nothing else. This was 

 also found to be inert against the insects mentioned. The insecti- 

 cidal principle of Pyrethrum flowers is not, therefore, in the non- 

 saponifiable portion of the petroleum-ether extract. 



The solution from the saponification after extraction with ether 

 was made sUghtly acid with sulphuric acid, and again extracted with 

 ether. These extracts were very dark red, almost black. After 

 washing with a little water, drying over calcium chlorid, and evapora- 

 ting the ether at room temperature in a current of air a sticky resin 

 was left. Special tests were made for phenols in tliis material, but 

 the results were negative. Tests on small portions with various sol- 

 vents failed to yield any crystalline product. 



^ The whole of the saponifiable portion was then dissolved in U. S. 

 P. ether, and about twice its volume of petroleum ether added. This 

 precipitated a very dark, sticky resm, which was filtered off. Tested 

 upon aphides, this resm proved to be inert. 



The filtrate from this resin, which contained the fatty acids, was 

 evaported to dryness, leaving a soft, yellowish, oily, soiu-smelling 

 residue. This material was shown to contain acetic and other fatty 

 acids, together with a pungent-tasting oily substance which was pres- 

 ent in too small an amount for further investigation. When sprayed 

 upon aphides feeding on nasturtium plants, the fatty acids injured 

 the leaves of the plants, but the aphides were miaffected. 



These tests show that saponification with alcoholic potash produces a 

 chemical change which destroys entirely the insecticidal action of 



