INSECTS AND INSECTICIDES 377 



may be most easily accomplished by suspending the copper 

 sulfate crystals in a sack near the top of the water. A solution 

 of copper sulfate is heavier than water. As soon, then, as the 

 crystals begin to dissolve, the solution will sink, bringing 

 water again in contact with the crystals. In this way, the 

 crystals will dissolve much sooner than if placed in the bottom 

 of the barrel. In case large quantities of stock solution are 

 needed, two pounds of copper sulfate may be dissolved in each 

 gallon of water, making the stock solution twice as strong. 



Slake the required quantity of lime in a tub or trough. Add 

 the water slowly at first, so that the lime crumbles into a fine 

 powder. If small quantities of lime are used, hot water is 

 preferred. When completely slaked or entirely powdered, 

 add more water. When the lime has slaked sufficiently, add 

 water to bring it to a thick milk or to a certain number of gal- 

 lons. The amount required for each tank of spray can be 

 secured approximately from this stock mixture, which should 

 not be allowed to dry out. Hydrated or prepared lime of 

 good quality may be substituted for the stone lime. Place 

 the required quantity in the barrel or tank and add water. 

 No slaking is required. Do not use air-slaked lime. 



To make a 5-5-50 bordeaux mixture, take 5 gallons of stock 

 solution, containing one pound of copper sulfate to a gallon 

 (or one half as much of the stronger solution) for every 50 

 gallons of bordeaux mixture required. Pour this into the 

 spray- tank. Add water until the tank is about two thirds full. 

 From the stock lime mixture add the required quantity. Stir 

 the mixture and add water to make 50 gallons. Experiment 

 stations often recommend the diluting of both the copper sul- 

 fate solution and the lime mixture to one half the required 

 amount before putting them together. This is not necessary, 

 and is often impracticable for commercial work. It is preferable 

 to dilute the copper sulfate solution. Never pour together 

 the concentrated stock mixtures and dilute afterward. Bor- 



