132 The Spraying of Plants. 



as in my experience the sediment is more coarse than when a 

 larger amount of water allows of a more free intermingling of 

 the two ingredients. Two gallons of water to every pound of 

 copper sulphate is a safe proportion, and the use of still more 

 water might be of benefit. All immediate chemical action has 

 largely ceased a few minutes after the lime and the copper 

 sulphate have been brought together, and the mixture may 

 then be diluted as desired, and immediately applied. 



The most convenient method of making the mixture is to 

 have a stock solution of definite strength, so that any desired 

 amount of the sulphate may be taken. This should be diluted 

 as already described, and then the milk of lime should be added. 

 This ingredient may also be prepared in large quantities before 

 using; it will keep indefinitely if kept covered with water. 



The sediment in the Bordeaux mixture remains in suspen- 

 sion much better during the first twenty-four hours after 

 the two ingredients are brought together; in fact, it settles 

 so slowly that an agitator is scarcely necessary during this 

 period. But after a day or two, probably on account of some 

 physical change in the mixture, the sediment rapidly settles, 

 rendering the use of an agitator essential for a uniform appli- 

 cation. To what extent this change affects the fungicidal 

 value of the mixture is not known, but if care is exercised in 

 keeping the old mixture well stirred, it is probable that good 

 results will follow. Such, at least, has been the writer's experi- 

 ence with Bordeaux mixture which was allowed to stand several 

 weeks before it was applied to the apple trees which were being 

 treated. 



If the Bordeaux mixture has been imperfectly made, or if it 

 is not applied with proper machinery, it will be found better to 

 strain either the lime before it is added to the copper sulphate 

 solution, or else the mixture before it is applied, the former 

 being perhaps the better plan. The mixture should be kept 

 constantly stirred when the application is made. 



The dried sediment has been used in place of the liquid form, 

 but the results were not equally satisfactory. It was found 

 that about four times as much material was necessary when the 

 powder was applied, and, besides, its efficiency was apparently 

 less marked. (See, also, DAVID'S POWDER.) 



Bordeaux mixture is said to possess a certain value as an 



