380 
Journal of Agricultural Research 
Vol. IX, No. n 
space at 70° F., and the time required for such quantity to kill house 
flies. Carbon bisulphid at the rate of 3 pounds to 1,000 cubic feet is 
compared with the benzene derivatives. As a low-boiling compound 
will penetrate grain better than a high-boiling compound, the possibili¬ 
ties of xylene, chlorbenzene, and brombenzene are at once apparent. 
Tests* of the value of these compounds in the fumigation of grain have 
not been made. Inasmuch as the vapor of many of the benzene com¬ 
pounds is explosive when mixed with air, one must observe certain pre¬ 
cautions, although in general they are far less explosive than carbon 
bisulphid. 
For the fumigation of animals a compound with a high boiling point is 
needed in order that relatively little of the material shall be in the air 
to be taken in by the animal or to irritate the eyes or nose. In this 
respect salicylic aldehyde is probably the best. The cost of this chemical 
is prohibitive for general fumigation; but, inasmuch as higher animals 
readily oxidize it to salicylic acid, which is very slightly poisonous, this 
compound might be used for the internal fumigation of horses to destroy 
bots as carbon bisulphid is now used. As previously stated, it has been 
decided to try out a large series of chemicals before selecting the best 
compounds for tests as to their practicable possibilities. 
SUMMARY 
Data are presented showing the toxicity of certain organic compounds, 
mainly from the aromatic series, to insects, particularly the house fly, 
and certain general relationships are indicated. 
(1) All the benzene derivatives tested proved to be more toxic to 
insects, molecule for molecule, than carbon bisulphid. 
(2) Physical characters, such as boiling point and vapor pressure, 
have more influence on the toxicity than chemical composition. 
(3) Up to 250° C. the higher the boiling point the more toxic the com¬ 
pound to insects. Beyond 250° C. the compound is usually so slightly 
volatile that not enough of the chemical will evaporate to be effective. 
(4) Lipoids are very soluble in compounds with low boiling points and 
but slightly soluble in compounds with high boiling points. 
(5) Compounds with low boiling points, although less toxic, owing to 
their great volatility, may give better results than compounds with high 
boiling points, particularly in the fumigation of grain. 
LITERATURE CITED 
(1) Bbchhold, H., and Ehkuch, P. 
1906. Beziehungen zwischen chemischer Konstitution tmd Desinfektions- 
wirkung. ... In Ztscher. Physiol. Chern., Bd. 47, Heft 2/3, p. 173- 
199. 
(2) Hirschfeldbr, A. D. 
1915. Brain lipoid as a haemostatic. In Lancet, v. 189, no. 4801, p. 542-543. 
Bibliography, p. 543. 
