Sept. 3, 1917 



Quassia Extract as a Contact Insecticide 



505 



Table III. — Influence of size of chips on the quantity of extract obtained by macerating 

 10 gni. of quassia chips in §00 c.c. of distilled water for 24 hours 



Chips. 



Sample 

 No. 



Size of chips. 



6 to 8 cm. long and i to2 cm. wide. . 

 4 to 5 cm. long and i to 1/2 cm. wide 

 2 to 3 cm. long and ^^ to 1}^ cm. wide 

 15 to 25 mm. long and 5 to 10 mm. 



wide 



7 to 13 mm. long and 3 to 5 mm. wide 



No. 5 powder 



No. 10 powder 



No. 20 to 40 powder 



No. 40 to 60 powder 



No. 60 to 100 powder 



No. 100 to 2CO powder 



No. 200 powder and finer 



Quantity of extract obtained. 



3.0 



is 



I- 

 I 



OsT 



0.0 



/^/^ ^ 



/6 



Total. 



It will be noted that 

 the quantity of ex- 

 tract dissolved by the 

 water is proportional 

 to the state of sub- 

 division of the chips. 

 This is especially true 

 with regard to the first 

 extraction. In figure 

 3, which shows graph- 

 ically the relationship 

 of the size of the 

 chips to the quantity 

 of extract obtained, 

 it will be noted that 

 relatively little ex- 

 tract is removed the 

 second time. It is 

 evident that a 24- 

 hour maceration will 

 extract from the 

 chips such a percent- 

 age of the total water- 

 soluble matter that 

 a second extraction 

 would be unprofit- 

 able. Reference to figure i will illustrate this further. It is noted that 

 the second extraction removes only one-sixth as much material as the first. 





s^ 



Fig. 2. — Graph showing the percentage of extract obtained by boiling 10 

 gm. of quassia chips ■with 500 c. c. of water for Yi i. 2, 4, 8, 16, and 24 

 hours, respectively. 



