Mar. 4. i9i8 Toxicity of Organic- Compouuds to hisect Eggs 



585 



The Perfection oil killed both the fully developed and freshly laid 

 eggs, leaving the partially developed uninjured except for the fraction 

 between 231° and 280° C. Other experiments with these two oils, which 

 will be published later, have shown that the Perfection oil is more toxic 

 than the Pennsylvania Best. Kerosene therefore has oils of low boiling 

 points which kill the freshly developed eggs and oils of high boiling points 

 which destroy the fully developed eggs, while the partially developed 

 eggs are most likely to hatch. 



Nineteen compounds were tested to determine the toxicity of their 

 vapor to insect eggs. The results of these experiments are given in Table 

 V, in which the compounds are arranged according to their boiling 

 points, from the lowest to the highest. The increase in toxicity with an 

 increase in boiling point is indicated by the smaller portion of a gram- 

 molecule necessary to kill in 15 hours. That the boiling point is not so 

 good an index of the toxicity of a chemical as its volatility is shown in 

 Table VI, where the compounds are arranged according to their volatility, 

 from the most volatile to the least volatile. A comparison of the two 

 tables shows a better correlation between volatility and toxicity than 

 between boiling point and toxicity. As was found in the work with the 

 housefly (5), chemicals having low boiling points are more valuable 

 for fumigation purposes due to the fact that a larger amount of the 

 vapor may be contained in the air. 



Table V. — Toxicity of the vapor of certain organic compounds (in millionths of a gram- 

 molecule required to kill in 75 hours' exposure). Compoundf arranged according to 

 their boiling points 



Compound. 



Ethyl ether 



Carbon bisulphid . . 

 Petroleum ether. . . 



Acetone 



Chloroform 



Methyl alcohol .... 

 Carbon tetrachlorid 



Ethyl alcohol 



Gasoline 



Thiophene 



Boiling 

 point. 



°C. 



35 

 46 

 40-70 



56.3 



61 



66.5 



78.1 

 78.4 

 70-90 

 84 



Toxicity 



(mil- 

 lionths of 

 a gram- 

 molecule). 



3, 468. 2 



555-5 

 243. 2 



558-0 



I, 232. o 



404. o 



284. o 



41. 1 



344- o 



Compound. 



Toluene 



Chlorpicrin . . 

 Chlorbenzene 



Xylene 



Bromoform . . 



Furfural 



Nitrobenzene 

 Nitroxylene . . 

 Nicotine 



Boiling 

 point. 



°C. 

 Ill 

 112 

 132 

 140 



151- 

 162 

 205 

 250 

 250 



Toxicity 



(mil- 

 lionths of 

 a gram- 

 molecule). 



104. O 

 2.8 



160.8 



29-5 



3-9 



1.8 



2.7 



3-3 

 1.8 



