159 



taking out a given quantity, the solution must be 

 thoroughly stirred, so that each lot is of the same con- 

 sistency. A besom or old whalebone brush is the best 

 stirrer. 



The lime should be slaked at least half-an-hour before 

 mixing. The copper solution is stirred into the 

 required amount of water, and then, after it has been 

 mixed with water to a creamy consistency, the lime 

 is poured into it and well stirred also. 



The lime is required to neutralise and precipitate the 

 copper. If this is not thoroughly effected there is 

 danger of cauterisation when the mixture is applied to 

 plants. Lime varies in quality, and the burning is not 

 always thorough, consequently it is impossible to state 

 definitely how much lime should be employed, although 

 when the lime is very good, 1 of lime to 2 of copper is 

 found to approximate it. To ensure that the copper 

 is neutralised, a solution of ferrocyanide of potassium 

 (yellow prussiate of potash a strong poison) can be 

 used at the rate ol 1 part of the crystals in 20 parts of 

 water. If a drop or two of this be allowed to fall on 

 the surface of the mixture there will be an immediate 

 dark-brown colouration where the drop falls if sufficient 

 lime has not been used. In this case more must be 

 added. If there is no reaction enough lime has been 

 used. 



Coarse lumps of lime should be removed before being 

 mixed with the solution, or they will tend to choke the 

 machine. 



When the hand machines are used the mixing is 



