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sects, and also to some extent by its corrosive action. The advantages 

 of fish-oil over ordinary laundry soap lie in the greater penetrating power, 

 in the fact that it remains liquid when cold, at much greater strengths, 

 and that fish-oil itself seems to be more fatal to insect life than other 

 animal fats. A. good soap can be made as follows: 



Concentrated potash lye 3^ pounds. 



Water 7\ gallons. 



Fish-oil i gallon. 



Dissolve the lye in water, boil, and to the boiling solution add the 

 fish-oil; continue to boil for two hours, and then allow to cool. Any 

 grade of fish-oil will answer 



"Whale-oil soap may be applied in the strength of one pound in four 

 gallons of water for brown or black plant-lice, and one pound in six 

 gallons for green plant-lice ; warm water should always be used when 

 dissolving it. 



"Soaps of all kinds are very useful in adding adhesiveness to liquid 

 mixtures when it is necessary to apply these to such vegetation as cab- 

 bages, turnips, peas, etc., which have their leaves covered with a waxy 

 secretion which prevents water from lying upon them. Any kind of soap 

 will answer for this purpose, and it may be remembered that one quart 

 of soft soap is about equal to one pound of hard soap." 



Another method for making home-made fish-oil soap is given by 

 Van Slyke and Urner, and is as follows :* 



Formula for Making Forty Pounds of Fish-oil Soap. 



Caustic soda 6 pounds. 



Water ii gallons. 



Fish-oil 22 pounds. 



"The caustic soda is completely dissolved in the given amount of 

 water and the fish-oil is added gradually under constant and vigorous 

 stirring. The combination occurs readily at ordinary summer tempera- 

 tures and the operation is soon completed. The mixing may be done in 

 any receptacle sufficiently large to contain the whole amount of material. 

 It would probably not be desirable to attempt to make more than 20 to 

 .40 pounds at a time, since the difficulty of thoroughly stirring a larger 

 mass would tend to make a complete combination less sure, thus render- 

 ing liable the presence of too much free alkali. Complete and thorough 

 stirring is essential to success. Caustic soda should be handled with 

 precaution, since in concentrated form it easily injures the skin. 



The authors show that when caustic soda can be got for 4^ cents 

 per pound and the fish-oil at 29 cents per gallon, the material for 40 

 pounds of soap costs $1.14, or 2.85 cents per pound. 



*New York Experiment Station Bull. No. 257, 1904. 



