48 FRUIT TREES AND THEIR ENEMIES 



Preparations of "soluble paraffin" mixed with 

 potassium sulphide are also made, these being 

 recommended for use against red spider and mites, 

 as well as for fungicidal purposes. 



Emulsions with basic sulphates. — The de-emulsifica- 

 tion mentioned as occurring sometimes in the case 

 of strong emulsions made with soap, never appears 

 to take place in those made with basic sulphates. For 

 use as a summer wash, that is, where caustic soda has 

 not to be added, the emulsions, both with copper 

 sulphate and iron sulphate, may be made, or may be 

 bought, of a strength tenfold that required for use ; 

 but with the washes for use in winter, it is only that 

 made with iron sulphate which can be obtained in a 

 concentrated form. 



The emulsions made with the sulphates of copper 

 and of iron for use in winter with caustic soda have 

 already been described under io<rand \od, respectively, 

 whilst the emulsion with copper sulphate for summer 

 use (Bordeaux emulsion) has been given under 9/7 and 

 9c It only remains to mention the wash correspond- 

 ing with the latter, but made with iron sulphate ; this 

 requires — 



{\6d) Iron sulphate . . .10 ozs. 



Lime (as a milk) . . 5 ozs. 



Paraffin (solar distillate) . 16 to 24 ozs. 



Water to make up to. . 10 galls. 



That the iron has been completely precipitated, 

 should always be ascertained in this case by testing 

 some of the clear liquid (before the paraffin is added) 

 with potassium ferrocyanide ; if a prussian blue 



