QUASSIIN AS A CONTACT INSECTICIDE. 3 



Quassine, the active principle of Quassia amara, is amorphous or crystalline. It has 

 been isolated by Winkler. It is colorless, inodorous, opaque, and inalterable in the 

 air, slightly soluble in water, much more soluble in water charged with salt or organic 

 acids, and in alcohol. 



Action on plants: Plants are not injured by spraying with aqueous extracts of 

 quassia. 1 



Quassia. — Constit.: Wood: Picrasmin, C 35 H 46 O 10 : quassin, C 10 H 12 O 3 (or, G 32 K 42 O 10 

 [?]); quassol, C 40 H 70 O — H 2 0; alkaloid; resin; mucilage; pectin. — Bark: Quassin; 

 alkaloid; resin; pectin. (Quassia amara contains 4 bitter principles; Picrxna excelsa 

 contains only 2): quassol, — - 2 



"Quassiin (C 32 II 42 O 10 ) may be obtained in a fairly pure state by exhausting quassia- 

 wood with hot water, precipitating the solution with neutral lead acetate, removing 

 the excess of lead from the filtrate by sulphuretted hydrogen and shaking the filtered 

 liquid with chloroform. On evaporation, the quassiin is obtained nearly colorless, 

 and, with some difficulty, in a distinctly crystalline condition. Quassiin has an in- 

 tensely and very persistent bitter taste. It is sparingly soluble in cold water, more 

 readily in hot water, and is easily soluble in alcohol. Its best solvent is chloroform, 

 which extracts quassiin readily from acidulated solutions. 



An aqueous solution of quassiin does not reduce Fehling's solution cr an ammonio- 

 nitrate of silver. The solid substance gives no coloration (or merely yellow) when 

 treated with strong sulphuric acid, or with nitric acid 1-25 sp. grL; nor is any color 

 produced on warming. * * * 



A solution of quassiin gives a white precipitate with tannin. The reaction is used 

 by Christensen, Oliveri, and others, to isolate quassiin from its solutions, and by 

 Enders to separate it from picrotoxin. In the author's hands the reaction has not 

 proved satisfactory. The liquid is very difficult to filter, and the filtrate still retains 

 an intensely bitter taste, showing that the precipitation is very incomplete. As an 

 analytical method the reaction is useless, but it is of some value as a qualitative test. 

 The test must be made in cold solution. Possibly a more complete precipitation of 

 quassiin by tannic acid might be effected in an alcoholic solution. 



Quassiin gives a brown coloration with ferric chloride. The reaction is best observed 

 by moistening a quassiin residue in porcelain with a few drops of a weak alcoholic 

 solution of ferric chloride, and applying a gentle heat. A fine mahogany-brown 

 coloration is produced." 3 



The quassiin used in the following experiments was extracted 

 according to directions given by Alien. 4 It was further found 

 that when boiled in alcohol a precipitate formed. This was fil- 

 tered off, the filtrate evaporated to dryness over a water bath, and 

 the resulting dark resinous material extracted with boiling water. 

 When extraction was complete a dark brown crusty material 

 remained. The resulting extract was light yellow and perfectly 

 clear. It was found to be intensely bitter. 



When cool this aqueous solution was extracted with chloroform, 

 evaporated over a water bath, and weighed and made into a per- 

 centage solution. 



i Bourcart, E., Insecticides, Fungicides and Weedkillers, p. 376. London, 1913. 

 2 Merkes 1907 Index, ed. 3, p. 366. New York, 1907. 



3 Allen, A. H., Commercial Organic Analysis, ed. 2 revised and enlarged, v. 3, pt. 3, p. 187-188, Phila- 

 delphia, 1896. 

 4 Except the solution was not acidulated before extraction with acid. 



