Summary. 377 



by completing pumps and appliances. Give particular 

 attention to a convenient wagon outfit. 



6. The Bordeaux mixture need not be made up 

 at each using in the exact numbers of the formula. 

 The copper sulfate may be permanently dissolved in 

 water and the lime may be slaked. When the mix- 

 ture is prepared, the stock solution of vitriol is di- 

 luted, the lime added, and the tank filled to the 

 required amount. 



7. Spraying is of small account unless the opera- 

 tor understands precisely what he sprays for. 



8. The time to spray is when the operation is 

 needed to protect the plant. This will vary, there- 

 fore, with every season and every different pest. In 

 general, apples and pears need spraying twice, first 

 when the fruit -buds open, but before the flowers 

 expand, and again when the blossoms fall. 



9. The presence of soluble arsenic in Paris green 

 may be determined by a test with sulfuret of hy- 

 drogen. 



10. Pure Paris green dissolves in ammonia, giv- 

 ing a rich, deep blue liquid. 



NOTE. Home-made arsenites of lime and soda are now used in some regions 

 Either can be used with Bordeaux mixture. When used with water, it is safer 

 to add freshly slaked lime. 



Arsenite of lime is made by boiling one pound of white arsenic in two to four 

 quarts of water until it is dissolved, then use this arsenic solution to slake two 

 pounds of good lime, adding water if necessary to slake it ; when slaked, add water 

 enough to make two gallons of this stock mixture. This may be kept in a tight 

 vessel and used as desired. Thoroughly stir the material before using. For most 

 insects one quart of the above to forty gallons of water will be sufficient. 



Arsenite of goda. The arsenic (one pound) may also be boiled with lonr 

 pounds of sal soda crystals in two gallons of water until dissolved, and this solu- 

 tion used in the same manner (with lime). 



