Circular 21 - Insectioides and Subsidiary Materials 19 
The liquid is noninflammable, heavy, 
colorless, and pungent, having the formula 
CCI5NQ2 , obtained by subjecting picric acid 
to the action of chlorine. Chloropicrin was 
used in the world war as a lethal, tear and 
vomiting gas. It has been used for killing 
rats in ships and as a soil disinfectant. 
Chloropicrin may be purchased in 1- 
pound glass bottles or in cylinders from 1 
to 100 pounds capacity at a cost of r>lo20 
per pound for 1-pound cylinders down to 85 
cents per pound in 100-pound lots. 
For manufacturers and distributors 
see numbers 8, 9> 36, and 58 of list at end 
of this circular. 
COAL TAR PITCH 
In insect control operations coal tar 
pitch is used to fill voids in concrete, 
cracking of walls or expansion joints, and 
where pipes or steel columns penetrate ground 
slabs of concrete, to block tennites from 
entering a building. 
Coal tar pitch is a dark-colored, 
viscous substance obtained as a residue in 
distilling coal tar. It is used in the manu- 
facture of varnishes, roofing paper, calking 
seams, as a preservative coating, and for 
insulating purposes. 
The material is shipped in barrels at 
$8.25 to $80 50 per barrel in less than carload 
lots, and at $19 to $22 for a single ton or 
in 50-pound containers for $1.50. 
