CHAPTER XII. 



MACHINERY AND DEVICES FOR THE DESTRUCTION OF 

 THE WORM.— Continued. 



IV.— PNEUMATIC COMPRESSION SaUIRTERS. 



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 aENEEATOES OF GAS, HOT-AIR, FUME, OR VAPOR PRESS- 

 URE, AS INSECTICIDE SQUIRTERS. 



[Plate 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 

 tlie 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 squirting 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 gas, 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 uozzles. 



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., aud vinegar or other acids 



253 



