ENEMIES OF PLANTS. 343 



() Prepare a Bordeaux solution with an excess of cop- 

 per sulphate, and add a few drops of potassium ferro- 

 cyanide. Note change. 



(f) Add potassium ferrocyanide to lime-water. See 

 p. 10 (d}. Note change. How does the result compare 

 with (a)l 



(a) Add potassium ferrocyanide to a solution of cop- 

 per sulphate. Note change. Ho\v does the result com- 

 pare with ()? 



Potassium ferrocyanide and copper sulphate 

 form a dark brown precipitate. If the Bor- 

 deaux solution shows a brownish color when 

 potassium ferrocyanide is added, what does it 

 indicate ? What would you do with the Bor- 

 deaux solution ? 



2. The Ammoniacal Copper Carbonate Solu- 

 tion. When the fruit is almost ready for mar- 

 ket it is advisable to use the ammoniacal copper 

 carbonate solution, as the Bordeaux mixture 

 stains the fruit and mars its appearance. 



Copper carbonate 5 ounces 



Strong ammonia 3 pints 



Water 50 gallons 



Add enough water to the copper carbonate to 

 make a thin paste ; then pour into it the ammonia 

 and mix thoroughly ; then add the water. Use 

 instead of the Bordeaux mixture whenever it is 

 desired to avoid the stain made by the Bor- 

 deaux. 



