306 Agricultural Chemistry. 



From the above soap solution, the miscible oil is prepared ac- 

 cording to the following formula : 



Soap solution 3% gallons 



Paraffine oil 40 



Rosin oil r > 



Water, as required by test. 



In the process of making the soap solution the kerosene should 

 be added while the soap is hot. The heavier oils should be stirred 

 into the soap solution at moderate temperatures. Freezing tem- 

 peratures should be avoided. The amount of water to be added 

 is a matter of experiment but it should be used in quantity suffi- 

 cient to produce an emulsion of creamy consistency. One gallon 

 of the soap solution or cmulsifier will make 8 to 14 gallons of 

 miscible oil and these 8 to 14 gallons will make from 100 to 210 

 gallons of spray material, according to dilution. 



Resin soaps, efficient against orange scale insects, are prepared 

 by boiling resin with carbonate of soda and diluting the solid 

 product with water. 



Fish oil soap and whale oil soap, prepared by boiling the oils 

 in potash lye and diluting with water, are effective against plant 

 and animal lice, but the commercial preparations are subject to 

 great variations in composition. 



Tobacco decoction depends for its value upon the poisonous 

 properties of nicotine. This alkaloid is soluble in water, and 

 hot water extractions of the stalk and waste of tobacco are used 

 as an insecticide. 



Gaseous insecticides are used against insects particularly dif- 

 ficult to attack. Hydrocyanic acid gas is by far the most effec- 

 tive substance in this class. It is produced from : 



Potassium cyanide, pure 1 ounce 



Sulphuric acid, commercial 2 " 



Water 4 " 



This is the quantity recommended for each 100 cubic feet of 

 space. The cyanide should be added last, having the mixture in 



