422 



JOURNAL OF ECONOMIC ENTOMOLOGY 



Vol. 15 



with the chemical results and the nicotine delivery, emphasized the 

 fact that the physical conditions of the clays played a role. For the 

 study of partial inhibition of the nicotine delivery by the colloidal 

 condition of the clays pure silica was mixed with different amoimts of a 

 given clay, and the mixtures impregnated with nicotine sulfate. The 

 results seemed to indicate that the nicotine evolution from carriers 

 mixed with nicotine sulfate is mainly a chemical phenomenon. 



Pure silica was thereupon thoroughly mixed with representative 

 chemicals in a ball mill and afterwards impregnated with nicotine 

 sulfate at a basis of 2 per cent nicotine. Some of the results obtained 

 are given in table 1. 



Table 1. 



Evolution of Nicotine from Silica Mixed with Chemical Activators, Impregnated 

 WITH 2 Per Cent Nicotine in the Form of Nicotine Sulphate. 



No. 



Carrier 



Percent nicotine after 48 hours. 



18.29 



12.82 



24.. 52 



11.03 



1.60 



3.53 



26.30 



2.16 



5.40 



The data in the tables are in all instances relative and therefore can be 

 used only for a comparison of the relative nicotine evolution from the 

 dusts imder certain definite conditions, as moisture, temperature, air 

 velocity and amount of carrier. 



An examination of the data in table 1 shows that the carbonates most 

 readily react with the nicotine sulfate. Calcium carbonate and Magne- 

 sium carbonate separately gave better results than any of the other 

 activators used, but a mixture of CaCOs and MgCOs proved to be best, 

 Magnesium seemingly acting as a catalyser. Such a mixture was found 

 in the form of dolomite (Magnesium limestone). Dolomite evolved 

 after 48 hours 31.7 per cent nicotine. The reaction between the nicotine 

 sulfate, taking the place of a weak acid, and the carbonates, is probably 

 through replacement of the sulfate radicle by the carbonate radicle 

 and a subsequent volitalisation of the nicotine. Determinations made 

 of soluble and insoluble sulfates before and after the subjection of the 

 mixtures to a stream of air showed a decided increase in insoluble sul- 

 fates (CaS04). 



It is apparent that under these conditions the influence of moisture 

 upon the evolution of nicotine from carriers must be considerable. The 

 data given in table 2 indicates conclusively the importance of moisture. 



