POSSIBILITIES AND LIMITATIONS OF CHLOROPICRIN AS 
A FUMIGANT FOR CEREAL PRODUCTS 1 
By R. N. Chapman, Associate Professor of Entomology, and A. H. Johnson, 
Strietmann Fellow in Agricultural Biochemistry, Minnesota Agricultural 
Experiment Station 2 
INTRODUCTION 
There has been a demand for a substitute for carbon disulphide 
for fumigating cereals and other stored food products to kill the 
insects wriich infest them. Carbon disulphide had many satisfactory 
properties, but its inflammability led insurance underwriters to adopt 
a ruling which renders an insurance policy void if carbon disulphide 
is used or stored on the premises of an insured building, and, likewise, 
practically all railroads have ruled against the use of it in their freight 
cars. 
The great amount of research work which was done on poisonous 
gases during the war has been drawn upon by workers m nearly 
every country, but it has not been easy to find a material sufficiently 
toxic to insects which would not at the same time be injurious to the 
materials to be fumigated. 
This paper is devoted to the results of a study of the toxicity of 
chloropicrin to certain insects which infest cereals, and to the effect 
of the chloropicrin on the cereals and their products. 
The chloropicrin used in the experimental work was obtained from 
the Edgewood Arsenal. It had a specific gravity of 1.6595, com¬ 
pared with water at 20° C. Bertrand (3) 3 states that chloropicrin 
J >repared by the action of calcium chloride on picric acid has the 
ollowing properties: Density at 16° C., 1.666; boiling point at 766 
mm. pressure, 112° C.; vapor tension at 15° C., 30.2 mm.; non- 
inflammable; 1.65 gms. soluble in a liter of water at 18° C. 
TOXICITY TO INSECTS 
SUMMARY OP LITERATURE 
The toxicity of chloropicrin to insects was noticed by Moore in 
1917 (15) while he was making a comparison of the volatility of 
organic compounds with their toxicity to insects. His table showed 
that, on the basis of the amount required to kill flies in 400 minutes, 
a gram molecule of chloropicrin was about 283 times as toxic as a gram 
molecule of carbon disulphide. He suggested that its toxicity was 
very likely due to its action as an enzyme poison. 
A second paper by Moore in 1918 (16) gave the results of someexperi- 
ments to determine the effects of chloropicrin on some of the insects 
which infest stored food products, on some of the products them¬ 
selves, on the germination of seeds, and also on certain fabrics which 
are used for clothing and other purposes. The experiments were 
performed, for the most part, in wooden boxes, and the report shows 
1 Received for publication May 24, 1924; issued December, 1925. Published with the approval of the 
director as Paper No. 470 of the Journal Series of the Minnesota Agricultural Experiment Station. 
2 The authors wish to express their thanks to the Underwriters’ Grain Association, and the Mutual 
Fire Prevention Bureau for valuable advice, suggestions, and financial assistance during the work. 
3 Reference is made by number (italics) to “ Literature cited,” p. 759. 
Journal of Agricultural Research, 
Washington, D. C 
( 745 ) 
Vol. XXXI, No. 8 
Oct. 15, 1925 
Key No. Minn. 57 
