28 DISEASES OF ECONOMIC PLANTS 



the minimum quantity of water. Thus a fine quality of 

 slaked lime is secured. After the lime is thoroughly 

 slaked enough water should be added to make a putty- 

 like mass. It should then be covered with more water 

 to keep out the air and may be used when needed. Since 

 this mass was originally weighed, estimate can be made 

 sufficiently accurate to determine the amount of the paste 

 to use in any given amount of Bordeaux mixture. 



In preparing the Bordeaux mixture from stock, measure 

 out the proper amount of stock solution of copper sulphate, 

 dilute it with half of the amount of water needed. In a 

 similar way measure out the proper amount of lime from 

 the stock and dilute it with the other half of the water in a 

 separate vessel. 



The lime should be passed through a fine wire strainer 

 of about eighteen meshes to the inch, or through cheese- 

 cloth, to remove particles of stone which would other- 

 wise cause great difficulty in the pump nozzle when 

 spraying. 



The two ingredients are now mixed each with one half 

 the amount of water called for in the formula. All 

 that remains is to pour them together slowly and stir 

 thoroughly. 



It is a matter of considerable importance that the stock 

 solutions be diluted before they are mixed with each other, 

 since the quality of Bordeaux mixture resulting from this 

 method is superior in several respects to that which would 

 be made if strong solutions were mixed together and after- 

 wards diluted. The Bordeaux should be freshly made 

 each time before using. 



An excess of soluble copper compounds in the completed 



