CARBON TRICHLORIDE AS AN ANTHELMINTIC, AND 
THE RELATION OF ITS SOLUBILITY TO ANTHEL¬ 
MINTIC EFFICACY 1 
By^MAURiCE C. Hall and Eloise B. Cram, Zoological Division , Bureau of 
Animal Industry , United States Department of Agriculture , 
INTRODUCTION 
On the basis of a very careful and 
extensive study of the correlation of the 
chemical composition and anthelmintic 
efficacy of a number of drugs, Caius 
and Mhaskar ( 8 ) 2 arrived at the conclu¬ 
sion that since chloroform showed con¬ 
siderable anthelmintic efficacy against 
hookworms, some related compound 
with a higher halogen content might 
prove even more effective, the anthel¬ 
mintic efficacy in the case of chloroform 
being correlated with its chlorine con¬ 
tent. By a shorter and less exhaustive 
line of reasoning, Hall (6) derived the 
same conclusion from substantially the 
same premises and reported that car¬ 
bon tetrachloride was such an anthel¬ 
mintic, his paper appearing the same 
month that Caius and Mhaskar pre¬ 
dicted the likelihood of a compound 
related to chloroform being effective 
against hookworms. Since chloroform 
(CHC1 3 ) and carbon tetrachloride 
(CC 1 4 ) show considerable efficacy 
against hookworms, it seems desirable 
that other related compounds should 
be investigated. In a study of miscel¬ 
laneous anthelmintics, Hall and Shil- 
linger (7) have tested ethylene dichlo¬ 
ride (C 2 H 4 CI 2 ), and find that it has 
some efficacy against hookworms, but 
less than chloroform and carbon tetra¬ 
chloride. Recently Hall and Shillinger 
(8) have reported that tetrachlorethy- 
lene (C2CI4) is apparently even more 
effective than carbon tetrachloride 
in removing hookworms, their paper 
covering experiments carried out subse¬ 
quent to those reported in this paper 
and continuing the same line of in¬ 
vestigation. The investigation re¬ 
ported in this paper pertains to carbon 
trichloride or hexachlorethane (C 2 C1 6 ). 
Carbon trichloride occurs in the 
form of colorless crystals which are 
insoluble in water, but soluble in alco¬ 
hol, ether, carbon tetrachloride, and all 
oils. Its insolubility in water is a con¬ 
spicuous property. When 1 gram was 
added to 2,000 c. c. of water there was 
no apparent diminution in the amount 
of it after two months, so little went 
into solution. The apparent solubility 
was decidedly less than 1 in 10 , 000 . 
Its odor is suggestive of camphor or 
turpentine. On theoretical grounds, 
certain possibilities as regards anthel¬ 
mintic action might be predicted from 
the chemical composition and physical 
nature of this substance. From its 
atomic structure one might conclude 
that it would be less effective than car¬ 
bon tetrachloride, since its proportion 
of chlorine to carbon is 3 : 1 instead of 
4:1. However, since the molecule 
actually contains more chlorine (6 
atoms) than does carbon tetrachloride 
(4 atoms), it might prove actually more 
effective. Actual test throws no light 
on this subject of chlorine content 
versus chlorine concentration, for the 
decisive factor in connection with its 
internal action is the physical factor of 
solubility. 
Anthelmintics have long been re¬ 
garded as relatively insoluble, more or 
less toxic, substances, which, by virtue 
of their relative insolubility, would re¬ 
main in the digestive tract to a great 
extent and poison the worms present, 
the host meanwhile absorbing very lit¬ 
tle of the poison and the drug being 
swept out of the digestive tract by 
means of a purge as soon as feasible. 
However, Hall (5) has noted as a prin¬ 
ciple of anthelmintic medication that 
“anthelmintics of the supposedly in¬ 
soluble type are not as insoluble as 
they are commonly supposed to be,” 
and cites the findings of Seidell in re¬ 
gard to thymol, to the effect that “of 
the thymol administered, from one- 
half to two-thirds is apparently de¬ 
stroyed or temporarily fixed in the 
body.” Thymol, we may recall, is 
soluble about 1 part in 1,100 parts of 
water at 25° C. Carbon tetrachloride 
is soluble 1 part in 1,250 parts of water 
at 25° C. 
As carbon tetrachloride appears to be 
about the least water-soluble of the 
anthelmintics in use for hookworms, 
1 Received for publication July 31, 1924; issued July, 1925. 
2 Reference is made by number (italic) to “ Literature cited,” p. 953. 
Journal of Agricultural Research 
Washington, D. C. 
( 949 ) 
Vol. XXX, No. 10 
May 15,1925 
Key No. A-98 
