LABORATORY EXERCISES 269 



67. Preparation of Bordeaux Mixture. 



Materials. Half a pound of copper sulfate, half a pound of 

 quicklime, five cents worth of potassium ferrocyanide. Two-quart 

 fruit-jars. A measure marked in ounces. 



Dissolve the potassium ferrocyanide in a two-ounce bottle of water 

 and label "poison." 



Prepare a stock solution of copper sulfate by dissolving the half- 

 pound in a two-quart jar of water. This will be at the rate of one pound 

 per gallon. 



Slake the lime and then dilute to two quarts. 



1. Place three ounces of the stock solution of copper sulfate in 

 one two-quart jar; fill nearly full of water, then add a little of the stock 

 solution of lime and test by adding a drop of potassium ferrocyanide. 

 If there is enough lime, the drop will remain yellow. If there is not 

 enough, it will turn a brick-red. About a half more lime than the test 

 requires should be used. This will probably take about three ounces 

 of the stock solution of lime if it is well stirred. Set aside to compare 

 with 2, 3 and 4. 



2. Put three ounces of the stock solution of lime in a second jar 

 and fill nearly full of water; then add three ounces of copper sulfate. 



3. In a third jar, put three ounces of copper sulfate solution and 

 fill half full of water. In a fourth, put three ounces of lime solution and 

 fill half full of water. Pour these into another jar at the same time. 



4. Put three ounces of copper sulfate solution into a jar, then add 

 three ounces of lime solution and add water to fill the jar. 



Set these four jars side by side. The material will gradually settle. 

 Measure the height of each one and fill out the following table: 



Height of column 

 Condition when mixed 



At End 30 



beginning minutes 



1 hour 



1 day 



1. Copper sulfate dilute . 



2. Lime dilute 



3. Both dilute 



4. Neither dilute . . 



Why does the material settle more rapidly in one than in another? 

 Which mixture would clog a spray nozzle moat? Which would be most 

 evenly distributed by spraying? 



