SPRAYING MACHINERY 125 



A word should be said about agitators. In most of 

 the barrel machines, as they come from the factory, 

 there is some sort of mechanical agitator to keep the 

 spray mixture stirred up. In larger machines the stir- 

 ring is accomplished by pumping back into the tank a 

 portion* of the liquid taken through the pump. This 

 agitation is important, especially with bordeaux mix- 

 ture. On rough ground, however, especially where 

 trees are small, and there is much driving from tree to 

 tree, the shaking of the wagon may give all the agita- 

 tion necessary. The presence of any considerable sedi- 

 ment in the bottom cf the tank after pumping out a 

 tankful of mixture indicates that more thorough stir- 

 ring is needed. Of course, it may, and probably does, 

 indicate also that the mixture is improperly made ; but 

 the poorer the original mixture the greater the demand 

 for vigorous stirring. 



With respect to pumps in general it must be remem- 

 bered that the cylinder is the vital organ. This should 

 be perfectly smooth and true, and should be lined with 

 brass or other non-corrosive material. Brass is the 

 material now most in use. All the other linings of 

 connecting working parts which come in contact with 

 the liquids should also be of brass. The nozzles are 

 practically always of brass. 



Power Sprayers Coming now to the power spray- 

 ers, in which the force is supplied from some other 

 source than human muscle, we find three general types 

 in common use. These are: (i) traction sprayers, (2) 

 engine or motor sprayers, and (3) those which operate 

 from air or gas pressure. It may be said at once that 

 any form of power sprayer, properly operated within 

 the scope of its adaptabilities, will give much better 

 results than hand power. Experience shows that the 



