No. 4.] MODERN POTATO CULTURE. 61 



inch (Xo. 50), or through a cheese-cloth backed by common 

 window screen. Stir constantly while adding the lime. 



Much time may be saved by preparing stock solutions. 

 While any proportions can be used, the following was found 

 in the spraying experiments made by the station a convenient 

 way : — 



The stock .solution of copper sulphate is made by weigh- 

 ing out 50 pounds of copper sulphate, placing it in a bag, 

 and suspending it in the top of a barrel containing 30 gal- 

 lons of water. The copper sulphate dissolves completely in 

 a few hours. The stock solution of the lime is prepared by 

 slacking 50 pounds of lime, and adding water so as to make 

 up to 30 gallons, and straining through No. 50 brass screen 

 cloth. To slack and strain this amount of lime takes less 

 than one-half hour. For use, 3 gallons of each solution and 

 44 gallons of water make up the formula given above. The 

 stock solution of lime should be kept well covered and be 

 thoroughly stirred before dipping out. 



Formula 3. Bordeaux Mixture and Paris Green. 



Paris green, £ pound. 



Bordeaux mixture, 50 gallons. 



Make a paste with the Paris green and a little water. Add 

 to the Bordeaux mixture and stir thoroughly. 



Formula 3a. Bordeaux Mixture and Lead Arsenate. 



Lead arsenate or disparene, 1 pound. 



Bordeaux mixture, 50 gallons. 



Formula 4. Pai'is Green. 



Paris green, £ pound. 



Lime (unslacked), 3 pounds. 



Water, 50 gallons. 



The standard remedy for the destruction of insects which 

 eat the foliage or fruit. The lime is added to prevent the 

 Paris green from burning the foliage. Slack the lime in a 

 little water, make into a thin paste. Mix the lime and Paris 

 green and add the remainder of the water. A stock solu- 

 tion of lime can be made as described under formula 2. 



