INSECTICIDES AND REPELLENTS 



25 



or even less of a 5-percent solution when properly dispersed. To ob- 

 tain coverage with such small amounts it is necessary to use a slow 

 delivery of a fine mist, and most of the ground equipment now avail- 

 able, except the fog or aerosol machines, cannot be adjusted to give 

 uniform distribution of minimal quantities. 



For small breeding places the cylindrical, hand-pumped compre- 

 ssion sprayer (fig. 2) is generally used (No. 8, table 4). A militar 



Figure 2. — A 2-gallon compressed-air sprayer. 



model is provided with four different nozzles — solid-stream, fan-spray, 

 cone-spray, and atomizing. The orifice diameters in the spray heads 

 are not to exceed 0.04 inch. This type of sprayer is operated at a 

 pressure of 20 to 30 p. s. i. Cylindrical compression sprayers of 3- 

 gallon capacity were formerly referred to in the Army as decontam- 

 ination type sprayers and also as Loftstrand sprayers. 



In civilian public-health- work similar sprayers have been modified 

 to provide the pressure by means of a small refillable carbon dioxide 

 tank attached to the spray cylinder. In another modification a valve 

 is installed at the top of the cylinder so that it can be filled with air 



