Sept. 3, 1917 



Quassia Extract as a Contact Insecticide 



509 



factor, all of the results recorded later than 9 hours after applying the 

 spray solutions were eliminated. 



Since the extract of quassia wood (see p. 510) contains constituents 

 other than the supposedly active one called "quassiin," it was considered 

 expedient to begin the experimentation with quassiin in as pure a form 

 as could be obtained on the market. Various solvents were used not 

 only on a small quantity of commercial quassiin powder labeled "purified 

 powder" but also on quassia chips and quassia powder. 



(a) Experiments with Quassiin Powder 



Before a discussion of the results obtained by using the extracts dis- 

 solved from the quassiin powder it was first thought advisable to deter- 

 mine the solubility of this particular powder in different solvents. 

 According to Schmidt (39), quassiin is difficultly soluble in water or 

 ether, but is readily soluble in alcohol, chloroform, or acetic acid. It 

 is also dissolved by caustic alkalies and concentrated acids, but not by 

 alkaline carbonates. 



To determine the solubility of the above-mentioned quassiin in (i) 

 distilled water, (2) in a 0.05 per cent sodium-carbonate solution, (3) in a 

 0.05 per cent lye solution, and (4) in a soap solution (1.8 gm. of potash- 

 fishoil soap to 1,000 c. c. of water, or 1.6 pounds of soap to 100 gallons of 

 water) , the following method was used : An excess of the quassiin powder 

 was placed in a flat i,ooo c. c. bottle containing 500 c. c. of distilled 

 water, and then the bottle with its contents was shaken by means of a 

 mechanical device for 5 hours; this process was repeated three times 

 by using the three other enumerated solvents, one at a time. After 

 filtering the mixture, 100 c. c. of each filtrate obtained were evaporated 

 in a tared dish, and the quantity of the solids remaining in the dish was 

 determined. These solids represented the extract from the quassiin 

 powder plus the solid matter contained in each solvent. It was there- 

 fore necessary to determine the quantity of solid matter in 100 c. c. of 

 each solvent not containing quassiin extract, in order to ascertain the 

 weight of the extract from the quassiin powder. The results obtained 

 are summarized in Table V. 



Table V. — Solubility of quassiin powder in various solvents 



