16 



PETROLEUM-OII. SERIES. 



Under the heading "Petroleum-oil series" are to be included kero- 

 sene and crude petroleum, either pure or in emulsion, and the so- 

 called miscible oils. 



Pure Icerosene treatment. — Pure kerosene has been more or less 

 recommended for spraying trees badly infested with the scale, but it 

 has never been very generally employed. There is no question of the 

 efhciency of such an application in the destruction of the insects, 

 but the great danger of injury to the plants precludes its general 

 application. Treatments of pure kerosene should be made only dur- 

 ing bright days and should be applied through a nozzle with a very 

 fine aperture. Only the minimum amount of kerosene necessary to 

 cover the trees should be given, and care is necessary that the liquid 

 does not puddle around the roots of the trees. 



Pure crude petroleum treatment. — Pure crude petroleum is used in 

 identically the same manner as pure kerosene, and the same cautions 

 as to its use should be remembered. The crude oil employed in the 

 East is known as "insecticide oil" and has a specific gravity of 43 

 to 45 degrees on the Beaume scale. 



Kerosene emulsion (stock solution 66 per cent oil). — Kerosene emul- 

 sion is made after the following formula: 



Kerosene (coal oil, lamp oil) gallons. . 2 



WTiale-oil soap or laundry soap (or 1 quart of soft soap) pound. . ^ 



Water gallon. . 1 



Dissolve the soap in boiling water; then remove vessel from the 

 fire. Immediately add the kerosene, and thoroughly agitate the 

 mixture until a creamy solution results. The stock emulsion may be 

 more conveniently made by pouring the mixture into the tank of a 

 spray pump and pumj^ing the liquid through the nozzle back into 

 the tank for some minutes. The stock solution, if well made, will 

 keep for some months, and is to be diluted before using. In order to 

 make a 10 per cent spray (the strength for trees in foliage), add to 

 each 1 gallon of the stock solution about 5| gallons of water. For 

 20 and 25 per cent emulsions (for use on dormant trees and plants), 

 use, respectively, about 2^ gallons and 1§ gallons of w^ater for each 1 

 gallon of stock emulsion. Agitate the mixture in all cases after 

 adding the water. The preparation of the emulsion will be simplified 

 by the use of a naphtha soap. No heat will be required, as the kero- 

 sene will combine readily with the naphtha soap in water when thor- 

 oughly agitated. Of naphtha soap, however, double the quantity 

 given in the above formula will be rec[uired, and soft or rain water 

 should be used in making the emulsion. In regions where the water 

 is "hard" this should first be broken with a little caustic potash or 

 soda, such as common lye, before use for dilution, to prevent the 

 soap from combining with the lime or magnesia present, thus liberat- 

 ing some of the kerosene; or rain water may be employed. 



[Cir. 124] 



