December, ’23] deong: volatility and toxicity of nicotine 493 
and at a high price; second, the release of nicotine from dusts varies 
with the type used and to a certain extent with the amount of moisture 
present; third, the stability of the nicotine as found in nicotine sulfate 
solutions is lost when alkali is added to ‘‘activate” it. Free nicotine is so 
volatile and subject to chemical changes that it has thus far been im¬ 
possible to store it for any length of time without loss. This emphasizes 
the value of the “self-mixing” duster which gives immediate use of the 
nicotine when first freed. Since volatility and toxicity are so closely 
related, it is apparent that a dust which releases nicotine very quickly 
is desired for high concentrations of volatile nicotine over short periods 
of time rather than a slow release over an extended period. To quote 
Professor Smith, “The greatest possibility of reducing the amount of 
nicotine used lies along the line of making it as quickly volatile as 
possible.” 
The data given in Table III show that the hydroxide compound releases 
the nicotine more slowly than the carbonates. Hydrated lime (Ca(OH) 2 ) 
gave a slower release of nicotine both in free and sulfate forms than did 
calcium or sodium carbonate (Na 2 Co 3 ). This agrees with the analyses 
given by Thatcher and Streeter (N. Y. Exp. Sta. Bui. 501). Professor 
Smith states in California Experiment Station Bulletin 336, that “Lime 
carbonate makes a very satisfactory filler but has no effect upon nicotine 
sulfate ...... Hydrated lime reacts with nicotine sulfate, forming free 
nicotine.” The carbonate of lime which Smith was using was princi¬ 
pally waste forms of lime which may account for the difference in results. 
Limited spraying tests with these two bases confirm the chemical 
analysis, i. e., the carbonate carrier is superior to the hydrate. 
A comparison of free nicotine and nicotine sulfate is also given and so 
far as the tests are completed, do not indicate a material difference be¬ 
tween these two forms of nicotine. It will be noted that free nicotine 
is less volatile with hydrated lime as a carrier than is nicotine sulfate 
from carbonate carriers. It is doubtful whether the added danger to 
the operator and the possibility of loss by volatilization would warrant 
the substitution of free nicotine for the acid compounds in the making 
of dusts, at least in the present stage of experimentation. 
Chairman R. E. Campbell: The next paper on spraying equipment 
for citrus trees will be presented by Mr. Herbert. 
