80 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 15 



Clay. Cla}- + 5% Calcium oxide, Clay+5% Calcium hydroxide, 

 Sanders' Mixture, Sanders' Mixture + 5% Calcium oxide, Calcium 

 hydroxide, Calcium hydroxide + 5% Calcium oxide. Clay + 50% 

 Calcium oxide. Calcium hydroxide + 50% Calcium oxide and Calcium 

 oxide. 



Fig. 1 . Diagram showing percent nicotine liberated after definite periods. Legend : 

 1 = Clay; 2 = Clay + 5% CaO; 3 = Clay +5% Ca(OH),; 4 = Ca (OH).; 5 = 

 Ca(OH). + 5% CaO; 7 = Sanders' mixture +5% CaO; 8 = Clay + 50% CaO; 

 9 = Ca(OH), + 50% CaO; 10 = CaO. 



Two Striking features appear in these tests — the first is found in the 

 fact that none of the mixtures throw off 25% of the nicotine within 

 the first 72 hours, or the period of kill. The second is that the clay 

 Calcium, oxide mix throws off only about 4% of its nicotine within the 

 period of kill and in spite of that fact seem.s to be one of the most effective 

 mixtures tried in the field. Of course, in the field tests the amount of 

 calcium oxide used was at least 8K% instead of 5% used in the labora- 

 tory tests. 



