The Mosquitoes of New Jersey 183 



acid. It was made up of resin, 150 to 200 pounds; soda, 30 pounds; 

 and carbolic acid, 150 gallons. This forms a black liquid resin soap. 

 It is said that this material emulsifies readily with fresh water but 

 not with alkaline or brackish water. It is specified that the phenol 

 content of the crude carbolic acid should be uniform and not less 

 than 15 per cent. It is further specified that the crude carbolic 

 should have a specific gravity of 0.97. 



METHOD OF MAKING 



The mixture is made under heat as follows : 



One hundred and fifty gallons of the carbolic acid is heated in a steel tank 

 fitted with a steam coil. When the acid is steaming hot, 200 pounds of 

 powdered resin is added and the mixture continuously stirred by means 

 of a paddle agitator, until complete solution is effected. Thirty pounds of 

 caustic soda (sodium hydroxide) is dissolved in 6 gallons of water, and 

 this is added to the resin-carbolic acid mixture. The heating and stir- 

 ring is kept up for about 5 minutes, and then a sample of the product is 

 withdrawn, and poured into water. If complete and rapid emulsion results, 

 the larvicide is ready and is withdrawn from the mixing tank into shipping 

 drums. If emulsion does not occur, or is incomplete, the heating is con- 

 tinued until a sample emulsifies satisfactorily. 



ADVANTAGES 



Le Prince and Orenstein^^ state the advantages and disadvantages 

 of this material as follows : 



The advantages of this phenol-resin soap larvicide are; 



1. High toxicity to mosquito larvae. A i to 5,000 emulsion kills full- 

 grown Anopheles larvae in from 3 to 10 minutes. 



2. Concentration. Being effective for practical use in a i to 5,000 emulsion, 

 only a relatively small quantity of the larvicide need be transported to a given 

 body of water. 



3. Uniformity of toxic power. This product, when carefully made, is 

 uniform in toxicity. 



4. Simplicity of composition. The manufacture of this larvicide requires 

 neither complicated apparatus nor highly skilled labor. 



5. Low toxicity to higher animals. It is practically harmless in ordinary 

 dosage or in dilution, to cattle, poultry, etc. 



6. Rapidity of toxic action. When used in the field, it killed all 

 Anopheles larvae and pupae in 10 to 20 minutes. 



7. Cheapness of the product. In Panama, the cost is about 18 cents a 

 gallon. 



'*Le Prince, J. A., and Orenstein, A. J., 1916, Mosquito Control in Panama. 



