328 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



soap is then separated from the water by addin^f weak salted lye. The 

 soap which floats is separated from the mother liquor. After com- 

 plete boiling in fresh salt h^e, the preparation of the soap is finished. 



2. Soft Soaps. — They consist of the potash salts of the most diverse 

 fatty acids, for all oils are used in their preparation. 



(a) Wlialc Oil Soap. — The salt of doeglic acid of whale oil. This 

 soap is gelatinous, and but slightly soluble in water. 



(b) Fish Oil Soaps. — The oils obtained by boihng decomposing 

 herrings and other sea fish are much uaed in America for the prepai^a- 

 tion of soap intended to be used against parasitic fungi. Sixty pounds 

 of caustic potash are boiled in 100 gallons of rain water, and 19 gallons 

 of cod oil or herring oil. After two hours' boiling, the soap is finished. 

 The soaps obtained are semi-solid. 



(c) Black Soap, Green Soap. — These have a very analogous com- 

 position, they are the ordinary soft or potassic soaps. These soaps are 

 gelatinous and soft, containing a great excess of lye and almost all the 

 glycerine. They are thus vary caustic, and act like feeble alkalies. 

 They are obtained by boiling caustic potash chiefly with linseed, colza, 

 and hemp-seed oil soap. The solutions are evaporated to a suitable 

 consistency. American arboriculturists prepare a cheap and efficient 

 soap by boiling together in 10 gallons of water, 12 lb. of lard, and 

 12 lb. of carbonate of potash. During boiling a milk of lime contain- 

 ing 5 per cent lime is added. Before using it to coat trees 1 part of 

 it is diluted with 2 parts of hot water. The bark of the trees 

 covered with this soap always remains fine and smooth. 



Insecticide Preparations. — Soap strengthens the action of certain 

 insecticides. It is thus often mixed with the most diverse organic 

 insecticides to form preparations capable of drenching the insects and 

 bringing the poisons ia contact with them better than aqueous solu- 

 tions do. Soap emulsions are made with petroleum, benzine, 

 carbon disulphide, and mixtures with ethyl alcohol, amyl alcohol, and 

 quassia. 



Composition and Preparation of a Few Insecticides. — 1. 

 Macerate in water for twenty-four hours H lb. of quassia ; boil and 

 mix the extract with 2^ lb. of soft soap in 10 gallons water (Taschen- 

 berg). 



2. Pour 2 gallons of boiling water on 3 lb. of quassia chips, 

 macerate twenty-four hours, add 5 lb. of soft soap in 2 gallons water. 



3. Emulsify 1 lb. of soft soap in 20 gallons water with 1 lb. carbon 

 disulphide. 



4. Emulsify 1 lb. of soft soap in 20 gallons water with 1 11). petioleum. 

 o. Emulsify 1 lb. of soft soap in 20 gallons water, 1 lb. carbon 



disulphide, and 1 lb. petroleum. 



6. Emulsify 5 lb. amyl alcohol, 5 lb. of a concentrated alcohol solu- 

 tion of soap, 10 lb. of carbon disulphide, and 5 lb. of petroleum, in 100 

 gallons water. 



Emulsions Nos. 3 to 6 have been used with success at the 

 Phytopathological Institute of Pisa. 



7. Dissolve 3 lb. of soft soap in rain water, add 6 lb. of amyl 

 alconol, and mike up to 10 gallons with rain water 



