Remedial Measures and Insecticides. xxxiii 



is not only in their effectiveness as insect-destroyers, but from their 

 being entirely without injurious effect on the treated plant. In 

 this respect they are perfectly safe in the hands of any person, in 

 contradistinction to all oily washes, which are very liable to be 

 injurious in greater or less degree, although the injury may be 

 insignificant, or perhaps not apparent immediately, or during the 

 first season.' . . . . ' The use of soaps is attended with certain 

 difficulties.' . . . . ' To be satisfactory for insecticide use it must, 

 when dissolved at the desired rate, say two pounds to the gallon 

 of water, remain a liquid capable of being sprayed with an ordinary 

 nozzle at an ordinary temperature. This may be determined by 

 a very simple test, and one which should be invariably given any 

 soap before it is accepted for spraying operations. It consists in 

 simply dissolving a small quantity of the soap at the desired rate, 

 and allowing it to cool.' 



Many soaps solidify or become gelatinous and tenacious on 

 cooling. These are useless for spraying purposes. The common 

 country soap of Ceylon has this defect. I have experimented 

 in a small way with soap mixtures ; but it is dif^cult to obtain 

 here a brand that combines suitability with cheapness. Such a 

 brand is a great desideratum. I find that one of the most useful 

 properties of the soap mixtures is to prevent the escape of the 

 young larvse by blocking up the natural exits, and on this account 

 the treatment is to be very strongly recommended. 



Kerosene Emulsion. — Soap is often combined with other 

 ingredients. Of these kerosene emulsion is the best known and 

 most widely used. As its efficacy and its effect upon plant life 

 very greatly depend upon the preparation of the mixture, great 

 care should be taken to accurately follow the directions. The 

 formula in general use is : — 



Soap i lb. 



Kerosene 2 gals. 



Soft water i gal. 



* Dissolve the soap in the water heated to boiling, then add the 

 kerosene (to the hot mixture), and churn it until a creamy fluid 

 results, which thickens on cooling, and adheres to glass without 

 separating into oily particles.' 



Whale-oil soaps are preferable, but any kind may be used. I 

 have personally made a very successful emulsion, employing the 

 common country soap, which seems to be particularly well adapted 

 to retaining the oil in an intimate mixture, and which, in this 



