SOLUTIONS FOR SPRAYING 139 



the slaking is well under way the sulphur should be 

 added. Then the heat generated by the slaking lime 

 will help to melt it. At this stage the kettle should 

 contain only lo to 15 gallons of water. Vigorous and 

 constant stirring of the mixture is necessary during 

 this period, which will occupy about 15 minutes. 

 When the lime is thoroughly slaked and the sulphur 

 dissolved the rest of the water (preferably hot) may 

 be added. The whole is then brought to the boiling 

 point and vigorously boiled for 40 minutes to an hour. 

 Most observers agree that a full hour of thorough boil- 

 ing is time and fuel well spent. During this cooking 

 the mixture changes to a dark reddish orange, very 

 characteristic and easily recognized after once seen. 

 This color is one of the best tests for a well-made 

 mixture and certainly no lime-sulphur solution should 

 be used unless this color appears unmistakably. 



Some sediment will be found in the bottom of the 

 kettle. This is mostly undissolved particles of lime 

 or unburnt bits of limestone. Any considerable 

 amount of this sediment indicates a poor grade of 

 lime. The solution should be strained before using, 

 and must be used at once, hot out of the kettle. Solu- 

 tion which stands overnight can be recooked and 

 used, but is not so good. The hotter the solution can 

 be put onto the trees the better, within practicable 

 limits. 



When considerable quantities of lime-sulphur mix- 

 ture are to be used it will usually be best to establish 

 a steam cooking plant. Any steam boiler will answer 

 for the generation of the steam, which can then be 

 conducted through pipes or steam hose to barrels or 

 tanks. Here the live steam is turned into the mixture 



