CHAPTER XII. 
MACHINERY AND DEVICES FOR THE DESTRUCTION OF 
TIIE WORM.— Continued. 
IV. — PNEUMATIC COMPRESSION SQUIRTERS. 
Various devices can be engaged to produce air, gas, or vapor pres- 
sure upon the liquid in a tight reservoir to eject the liquid contained, 
and such pneumatic compression ejectors may be used instead of force- 
pumps, with the various distributers of poison to constitute insecticide 
machines. These I have classified under four subsections, viz: 
1. Expansion generators. 2. Rotary force blasts. ,3. Oscillating 
pneumatic bellows. 4. Pneumatic reciprocating pumps. 
EXPANSION GENERATORS OF GAS, HOT-AIR, FUME, OR VAPOR PRESS- 
URE, AS INSECTICIDE SQUIRTERS. 
[ Pl.it, • XXXV.] 
The expansile power from the generation of these states of matter is 
Utilized by substituting a generator for the force-pump or bellows of 
the apparatuses elsewhere described. In such combinations I have found 
the gas-pressure process to work very satisfactorily. By the methods 
set forth it will be one of the easiest, most economic, and most effectual 
ways of applying insecticides. 
Gas-pressure generators have been used with great success in small 
fire : extinguishers. The employment of these or similarly constructed 
apparatuses has been suggested for squiiting poison on crops. The ex- 
pense of such machines and their chemicals has proved too great, and 
there is in their operation a great waste of the ,^as. and of the chemicals 
which does the crop no good and which can be avoided by a different 
method according to which the gas is generated and its pressure ap- 
plied for squirting poison in a more economic manner. By fire-extin- 
guishers the chemicals and the gas itself are partly squirted away with 
the liquid. These are not mixed with the liquid in the generator which 
my experiments led me to prefer. The gas is passed in on top of the 
poison, pressing it downward in the barrel or reservoir from the base 
of which it squirts out through a simple or branched pipe or pipes and 
their terminal nozzles. 
Carbonic anhydride is the most cheaply and easily made and used. This 
is best prepared by the action of sulphuric acid on bicarbonate of soda. 
Carbonates of lime, as marble dust, &c, and vinegar or other acids 
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