192 
TREES AS GOOD CITIZENS 
ferent lines. This substance kills by suffocation and is 
used against borers, by injections into the openings of their 
tunnels. The vapor of carbon disulphid is heavier than 
air, and when it is injected the vapor sinks. The injection 
is made by using a squirt oil can or a dropper, such as is 
employed in filling fountain pens. After the injection has 
been made the hole must be promptly plugged with some 
such material as grafting wax, putty or soap, to prevent 
the escape of the vapor. Carbon disulphid must be handled 
with care. It is highly inflammable and , when inhaled freely , 
it is poisonous. 
Spraying Apparatus. —For use in spraying small trees 
a hand atomizer is adequate. In general appearance this 
resembles a tire-pump. It is made of copper, brass or 
heavy tin, and holds about a quart of liquid. 
A small compressed-air pump is convenient for spray¬ 
ing operations on a small scale. This pump resembles the 
fire extinguishers seen in factories and office buildings. It 
is made of brass or galvanized sheet steel, and holds from 
3 to 4 gallons. It is carried by means of a shoulder strap. 
In preparing it for use the liquid is poured into the tank, 
the opening closed and air pumped in to provide pressure 
for forcibly expelling the liquid. 
A barrel hand-pump outfit, holding approximately 50 
gallons, may be used for spraying a limited number of 
moderate sized trees like apple trees. The working parts 
of the pump must be of non-corrosive metal, such as 
bronze or brass. The pump may be mounted on either 
the head or side of the barrel, and the whole outfit placed 
on a wagon or on skids, for convenience in moving from 
tree to tree. 
Next in size and capacity above the barrel hand-pump 
outfit is the double action hand-pump, employed with 
150 or 200 gallon tank, the tank mounted on the running 
