THE PREPARATION OF INSECTICIDES 91 



1 Ib. of caustic soda, and then add to these f pint of 

 fish oil. Cover these with about 2 in. of water and boil 

 until the solids have dissolved. Slowly add water, 

 keeping the mixture up to boiling point, until the whole 

 is made up to 3 gallons. This constitutes the stock 

 solution. Before application dilute at the rate of 6 gallons 

 of water to 1 gallon of the stock solution ; rain-water is 

 preferable, as this is not impregnated with lime or other 

 minerals. 



The diluted mixture should be sprayed on insect- 

 infected trees ; 100 gallons is sufficient to treat an acre 

 of cocoa trees, and one man should deal with half an acre 

 in a day. 



Resin Compound. Pound 4 Ib. of resin and 3 Ib. of 

 common washing soda in a mortar and mix them with 

 1 gallon of water. Boil until the solids have completely 

 dissolved, then slowly make up the mixture to 5 

 gallons by the addition of water. Thoroughly boil until 

 a clear brown colour is obtained. This is the stock 

 solution, and should be diluted with 25 gallons of soft 

 water previous to application. 



Kerosene Emulsion. To prepare this dissolve hard soap 

 in the proportion of 1 Ib. to every 2 gallons of boiling 

 water. When these have been thoroughly mixed, and 

 while the water is hot, slowly add 4 gallons of kerosene 

 and well churn with a syringe or force-pump until a 

 cream is formed and the oil has become completely in- 

 corporated in the soap solution. This forms the stock 

 solution, and if it has been properly mixed, no trace of 

 oil will be apparent on the surface even after it has been 

 standing several days. Before application this should be 

 made up to 66 gallons with rain-water or soft water. 



Whale-oil Soap Solution. This is made by mixing 

 whale-oil soap at the rate of | Ib. to every gallon of 

 boiling water. 



Tobacco Solution is prepared as follows : Steep tobacco- 

 leaf, in the proportion of 1 Ib. to every gallon of water, 

 for 24 hours, and afterwards strain the resulting liquid 

 through a cloth. Dissolve 1 Ib. of hard soap to every 

 10 gallons of water. Mix the tobacco water and the soap 

 solution at the rate of 1 gallon of the former to 10 gallons 

 of the latter, and it is ready for use. 

 Resin and Whale-oil Soap Mixture. Take 4 Ib. resin, 



