6 BULLETIN 167, U. S. DEPARTMENT OF AGRICULTURE. 
dichlorobenzene for 24 hours at an average temperature of 79° F. Two days later the seed was examined. 
and showed no material injury from the experiment, sprouting about as usual. 
Note.—Preliminary experiments with para-dichlorobenzene have been conducted along the following 
lines: 1. Para-dichlorobenzene introduced into insect collection boxes for the eradication of museum pests. 
2. Para-dichlorobenzene in combination with formaldehyde and potassium permanganate as an insecticide 
and germicide. 3. Para-dichlorobenzene made into a paste by adding paraffin and resin in the presence 
of heat, as a substitute for grafting wax. The above paste to be applied in the burrows of borers in shade 
trees. 4. Further experiments on the effect of para-dichlorobenzene, if any, on tender plants. ‘5. The 
effects, if any, of para-dichlorobenzene on animals, when taken internally in small doses. these experi- 
ments green food, such as Kale, cabbage, and clover, were put in a jar heavily charged with para-dichloro- 
benzene vapors and fed twice daily to herbivorous animals, such as rabbits and guinea-pigs. In these 
experiments the writer has not as yet reached any definite conclusions, and therefore reserves their pub- 
lication until further experiments along these lines are completed. 
CONCLUSION. 
From the foregoing observations and experiments the writer 
concludes that para-dichlorobenzene, used as directed in the preceding 
pages, acts as an excellent fumigant against the following insects: 
(1) Stored-product insects. 
(2) Case-bearing clothes moths. 
(3) Roaches and ants. 
(4) Museum pests. 
(5) Miscellaneous house insects, including flies, carpet beetles or buffalo 
moths, book lice, silverfish, mosquitoes, centipedes, and miscellaneous 
larder insects. 
It is also an effective substitute for potassium cyanid in collecting 
bottles. 
CHEMICAL AND PHYSICAL PROPERTIES OF PARA-DICHLOROBENZENE. 
At the request of Dr. Chittenden the following data were kindly 
furnished by the Insecticide and Fungicide Laboratory, Miscella- 
neous Division, Bureau of Chemistry: 
We have made an examination of the sample of dichlorobenzene submitted by you 
for examination on December 22, 1913, and find that this product is practically pure 
para-dichlorobenzene (C;H,Cl,). We have looked up some references in the litera- 
ture in regard to this substance and give you the following information based thereon: 
Dichlorobenzene is a product derived from benzene by the replacement of two of 
the hydrogen atoms by chlorine. There are three dichlorobenzenes, designated 
eriho, meta, and para, the structural formulas of which are: 
Ce cL cE 
Cc Cc 
Ao 4S 
ON Ne NS 
ie ¢ f 
Peg H cl 
ORTHO META PARA 
All three have the empirical formula C,H,Cl,. Ortho and meta dichlorobenzenes 
are liquids, the former boiling at 179° C.-and the latter at 172° C. 
Beilstein, in his Handbuch der organischen Chemie, III Auflage, 1896, Band II, 
page 44, gives three methods for the preparation of para-dichlorobenzene (in the 
German, p-dichlorbenzol): 
*y 
£ 
