40 
BULLETIN 1451, U. S. DEPARTMENT OF AGRICULTURE 
PARATOLUIDINE 
Paratoluidine (C 6 H 4 CH 3 NH 2 ) is a white crystalline substance. 
Applied to the soil in 8-inch pots in which barberries were growing, 
5:2 grams failed to cause the death of the plants in 30 days, though 
most of the leaves died. The action was much slower than that of 
orthotoluidine. Therefore, field tests were not made with this 
substance. 
WATER-GAS DRIP OIL 
Water-gas drip oil is a substance of varying composition and con- 
sistency, which condenses in gas mains and is caught in " drip pots " 
whence it is removed. In most, cases no use is made of the drip oil, 
and it is disposed of in the least offensive way. It can be purchased 
from gas companies at about the cost of handling. 
The water-gas drip oil used in these experiments was a thin watery 
liquid, almost black in color, with a strong, somewhat unpleasant, 
and very persistent odor. Some companies refer to thick liquids as 
drip oil. The substance used is said to consist of benzol, toluol, 
xylol, and higher homologues of the benzene series, napthalene, tarry 
residues, water, very small quantities of ammonium "chloride, sulphur, 
and unsaturated hydrocarbons of the ethylene and acetylene series. 
Quantities of this drip oil were obtained from several local gas com- 
panies at a cost, including the barrels, of about 10 cents a gallon. 
In the greenhouse an application of 80 cubic centimeters of water- 
gas drip oil to a barberry growing in an 8-inch pot killed the plant 
in 21 days. Field tests also were made, the results of which are given 
in Table 16. 
Table 16. — Summary of treatments of individual, marked barberry bushes with 
water-gas drip oil 
Date of treat- 
ment 
Date of final 
observation 
Quan- 
tity of 
chem- 
ical per 
bush 
Method 
of appli- 
cation 
Bushes cut 
off' or left 
standing 
Location of area 
Bushes 
treated 
Bushes 
killed 
Per 
cent- 
age 
killed 
Oct. 1, 1921 
Do 
Oct. 14,1921 
Do 
July 10,1922 
Do 
Oct. 17,1922 
Do 
June 23,1923 
May 29,1923 
May 27, 1923 
do 
June 3, 1923 
do 
June 15,1924 
.....do 
Gallons 
0.6 
.82 
1.14 
1.14 
1.0 
1.0 
1.0 
1.0 
Drench. 
...do 
...do 
...do 
...do 
...do 
...do 
...do 
Cutoff.... 
Standing.. 
Cut off.... 
Standing.. 
Cut off 
Standing.. 
Cut off.. .. 
Standing.. 
Black Earth.Wis. 
do 
Marshall, Wis 
do 
Gurnee, 111 
do 
do 
do 
54 
17 
21 
21 
19 
19 
5 
5 
52 
17 
21 
21 
16 
18 
5 
4 
96 
100 
100 
100 
84 
94 
100 
80 
Total..- 
161 
154 
96 

Though treatments were made only in July and October and the 
quantities used were not varied greatly, the results were very prom- 
ising. From these limited tests it would seem that, considering 
merely cost and effectiveness, drip oil would rank well toward the 
top of all the chemicals tried on barberries in the field. There are 
several disadvantages, however, in its use for barberry eradication 
in an extensive way. First, it is of unknown and varying consti- 
tution. Drip oils obtained from different gas plants would vary to 
some extent, and the action of a specific one on barberries could be 
