202 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



spray is soon gone, and it only kills the insects which are wet 

 with its spray. It is generally applied warm. In making the 

 soap the ingredients are placed in a closed kettle with enough 

 water to cover, and are boiled for two hours, when all will be 

 united into a soap. In diluting, only a little water should be 

 added at a time, and stirred in ; or, better, hot water should be 

 used, because of the danger of chilling the soap and causing it to 

 harden, when it is almost impossible to dissolve it again. The 

 proportions are 8 lbs. of resin, 2 lbs. of standard caustic soda, 

 and one pint of fish oil for 40 gallons, for use on trees in foliage,* 

 and the same for 25 gallons to 30 gallons for winter use. 



Kerosene. — There has recently been placed on the market 

 a device for mixing kerosene with water in the pump as it is 

 being applied, and with very good results. Full directions as to 

 proportions accompany the device, and we will here only discuss 

 the precautions to be observed. These are, chiefly, the use of a 

 nozzle capable of producing a very fine mist, and applying the 

 spray so that the drops do not run together, i.e., holding the 

 nozzle as far as possible from the plant, and not applying 

 too much. Pure kerosene has great penetrating power, perhaps 

 the greatest of all the insecticides, and, with the above pre- 

 cautions, can be safely used. 



Kerosene Emulsion. — While not as cheap as resin soap, 

 kerosene emulsion is easier to make, and, in small quantities or 

 where the conveniences for boiling are not at hand, is the most 

 satisfactory remedy. Like resin soap this spray kills by contact. 

 The ordinary form of the emulsion is something of an art, to be 

 properly manufactured. The ingredients are two parts of kero- 

 sene to one of sour milk or of strong soap solution. The latter 

 must be made boiling hot and added to the kerosene, and the 

 whole pumped through a spray nozzle for fifteen minutes. After 

 pumping a few minutes, the whole mass will become beautifully 

 creamy and apparently perfectly emulsified ; but if a little is 

 placed in water it will be seen that some of the kerosene sepa- 

 rates out and rises to the surface. When the emulsion is perfect 

 there will be no separation when diluted. If the soap is of poor 

 quality or the water is hard, more soap must be used ; and, on 

 the other hand, if both are good, not as much is needed as 



* It is very doubtful whether in England 2 lbs. of caustic soda to 

 40 gallons of water is not too strong a mixture for trees in leaf. — Ed. 



