EXERCISE XXXVI. 

 BORDEAUX AND OTHER PROTECTIVE MIXTURES. 



Supplies for a Laboratory Section of Twelve. One-half pound of copper sulphate; one-half pound of quick- 

 lime (lime not slacked); 24 test tubes; litmus paper; three 200 cc. cylindrical graduates; balance; one one-liter 

 solution bottle; five 250 cc. beakers; five 500 cc. beakers; wire nails; 10 grams of potassium ferrocyanide dis- 

 solved in 100 cc. of water and labeled "Poison' 1 ; small strips of ordinary paper; one pint of kerosene; one cake 

 of soap ; one-half pound of resin ; one-half pound of beeswax ; one-half pound of tallow ; twelve evaporating dishes ; 

 one ball of knitting cotton or pieces of calico. 



INTRODUCTION. Among the various substances used for the protection of plants are 

 the following: 



(1) Fungicides — antiseptic material used to cover those portions of the plant susceptible 

 to diseases caused by fungi. Reference. "Elements of Agriculture," Warren, Articles 228- 

 230. 



(2) Insecticides — materials used to to destroy insects. Reference. "Elements of Agricul- 

 ture," Warren, Articles 235-236. 



(3) Protective coverings for plant wounds. 



Part A. Bordeaux Mixture — A Fungicide. 



1. (a) Test a solution of copper sulphate with litmus paper to determine whether it 

 be acid or alkaline, (b) Test water to which quicklime has been added. Is it acid or alka- 

 line? (c) Place a piece of red litmus paper in the copper sulphate solution. Slowly add 

 limewater, stirring it as it is added. Does the red litmus paper change color? (d) What 

 would a change in color indicate? When a solution of copper sulphate is not mixed with 

 sufficient lime it is injurious to growing plants. Copper sulphate solution may, however, be 

 applied to dormant plants with but little fear of injury. 



2. (Classroom experiment.) The formula for Bordeaux mixture is usually given as fol- 

 lows: ■. 



Copper sulphate, 5 pounds. 



Quicklime (lime not slacked) 4-5 pounds. 



Water, 50 gallons. 

 Since these units of measure are not convenient for demonstration work it will be neces- 

 sary to reduce them to units more readily handled. It may be shown by calculation that 5 

 pounds of material to 50 gallons of water gives about the same strength of solution as 5 grams 

 of the material to 400 cubic centimeters of water. Since this is true, the above formula might 

 be restated as follows: 



Copper sulphate, 5 grams. 



Quicklime (lime not slacked) 4-5 grams. 



Water, 400 cubic centimeters. 

 For this experiment it is necessary to have at hand a liter (1,000 cubic centimeters) of 

 water in which has been dissolved 25 grams of copper sulphate. Also five 250 cc. beakers, 

 each containing 200 cc. of water to which has been added quantities of quick lime varying 

 in order from 1 to 5 grams. 



Measure out 200 cc. of the copper sulphate solution. Now pour the 200 cc. of copper 

 sulphate solution and the 200 cc. of water containing 1 gram of quicklime into a 500 cc. 

 beaker at the same time. In the same manner pour together 200 cc. of copper sulphate- 

 solution and 200 cc. of water containing 2 grams of quicklime. Continue until you have mixed 

 200 cc. of copper sulphate solution with each of the remaining 200 cc. samples of water and 

 lime. 



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