482 FRUIT INSECTS 



of the pentasulfid. To insure the complete union of the sulfur 

 and lime, it is necessary to boil the mixture about one hour. 

 If boiled much less than an hour, some of the ingredients will be 

 left in a free and insoluble condition, forming a sediment. If 

 boiled much more than an hour, insoluble compounds of calcium 

 and sulfur are formed, which go to increase the quantity of 

 sediment. 



To avoid the formation of sediment in the solution, it is im- 

 portant that only high grade lime be used, that the lime and 

 sulfur be combined in proper proportions, and that the mixture 

 should not be cooked in too concentrated a form. 



To obtain the best results, use lime guaranteed to contain at 

 least 95 per cent calcium oxid ; lime containing less than 90 per 

 cent should be avoided. Lime containing more than five per 

 cent magnesium oxid should never be used, as the presence of the 

 magnesium causes an unnecessary loss of sulfur, produces the 

 poisonous hydrogen sulfid gas (H2S) and increases the amount 

 of sediment. In ord(^r to avoid the presence of uncombined 

 lime or sulfur in the mixture, twice as much sulfur as lime is 

 used (90 per cent calcium oxid), since this is the proportion in 

 which they combine under these conditions. 



Several formulas have been used in the past, but the follow- 

 ing, worked out at the Geneva Agricultural Experiment Station, 

 is on the whole the most satisfactory for commercial work. 



Homemade concentrated lime-sulfur solution. 



Lump lime f9|^ P^r cent calcium oxid 38 pounds 



[90 per cent calcnim oxid 40 pounds 



Sulfur 80 pounds 



Water 50 gallons 



Make a paste of the sulfur with about 10 gallons of hot water. 

 Add the Hme. As the lime slakes add hot water as necessary 

 to prevent caking. When the lime has slaked add hot water to 

 make 50 gallons and boil one hour, stirring constantly. Water 



