FUNGICIDES, ETC. 287 



simple construction that can easily be taken apart for 

 cleaning or repairs. The suction portion of the pump 

 should be provided with a good brass screen. Some 

 provision should be made for agitation. Jet agitators 

 should be avoided on hand-pumps as they are too 

 wasteful of power. In short, a good spray pump should 

 be simple of construction, easy to operate, maintain 

 equal pressure, be non-corrosive, and furnish good 



agitation. 



Power-sprayers may be roughly divided into two 

 classes (1) those in which the power is applied to a 

 powerful pump by means of some sort of an engine, 

 (2) those where the power is supplied by a compressed 

 gas. Carbon dioxide or air are the two gases most 

 commonly used. 



Engine-Sprayers. The most popular engine used is 

 the gasoline engine, although a steam engine can be 

 used. Gasoline engines have a great advantage over 

 steam engines in that they are much lighter and can 

 be built more compactly, thus occupying but little 

 space. Gasoline engines are easy to operate, and give 

 the most general satisfaction of all types of power- 

 sprayers. The engine should have at least 1|- horse- 

 power, but a 2 horse-power will be found to be more 

 satisfactory. 



Gas Sprayers. Gas sprayers may be traction or 

 non-traction. A traction sprayer is one where the 

 spraying power is derived from the wheels of the spray 

 wagon or cart. The wheels are attached to power- 

 pumps which handle either liquid or air, and the spray 

 mixture is pumped into a strong air-tight chamber, 

 from whence it is driven by the compression of the air 

 in the chamber. Such sprayers are very satisfactory 

 for spraying garden crops, such as tomatoes, potatoes, 

 etc., where a continuous spray is maintained as the 

 outfit moves across the field. Some of them are also 

 very satisfactory for orchard work. 



Non-traction gas sprayers are operated by com- 

 pressed gas that has been compressed in tanks that are 



