374 



Heating is unnecessary in making the milk emulsion, which 

 otherwise is churned as in the former case. The change from a 

 watery liquid to a thick buttery consistency, much thicker than with 

 the soap, takes place very suddenly after three to five minutes' agita- 

 tion. With sweet milk difficulty will frequently be experienced, and 

 if the emulsion does not result in five minutes, the addition of a little 

 vinegar will induce prompt action. It is better to prepare the milk 

 emulsion from time to time for immediate use, unless it can be 

 stored in quantity in air-tight jars; otherwise it will ferment and 

 spoil after a week or two. 



The Distillate Emulsion. This wash was originated by Mr. F. 

 Kahles, of Santa Barbara, Cal. It has been recommended by the 

 California State Board of Horticulture and has found very general 

 use in the citrus sections of the State. It is substantially an emul- 

 sion of crude petroleum, made in the same way as the kerosene emul- 

 sion described above, except that a greater amount of soap and only 

 half as much oil proportionately is used. The lessened quantity of 

 oil enables it to be made comparatively cheaply, and in spite of this 

 reduction in the oil, the wash is, if anything, stronger than kerosene 

 emulsion, judging from the experience of the writer with both these 

 washes in southern California. 



It is termed distillate spray, because the oil used is a crude dis- 

 tillate of the heavy California petroleum. The product used for pre- 

 paring the emulsion should have a gravity of about 28 Baume, and 

 is the crude oil minus the lighter oil, or what distills over at a tem- 

 perature between 250 and 350 C. In general characteristics it is 

 very similar to lubricating oil. The emulsion, or, as it is generally 

 known, cream, is prepared as follows: Five gallons of 28 gravity 

 distillate; 5 gallons of water, boiling; 1 to l a /2 pounds of whale-oil 

 soap. The soap is dissolved in hot water, the distillate added, and the 

 whole thoroughly emulsified by means of a power pump until a 

 rather heavy yellowish, creamy emulsion is produced. The product 

 is very similar to, but rather darker in color than the ordinary kero- 

 sene emulsion. For use on citrus trees it is diluted with from 12 

 to 15 parts of water, the stronger wash for the lemon and the weaker 

 for the orange. The distillate cream is commonly prepared and sold 

 by oil companies or individuals at from 10 to 12 cents a gallon, 

 making the diluted mixture cost in the neighborhood of a cent a 

 gallon. 



The distillate spray has the same range of application as kero- 

 sene emulsion. In California it has been used extensively for the 

 spraying of citrus trees and when so used has been often charged 

 with injury to trees, and especially resulting in spotting of fruit. 

 If this spray be applied to citrus plants in spring and summer, there 

 is danger of the spotting and dropping of the young fruit and leaves. 

 Where several applications may be necessary each year, gas fumiga- 

 tion is undoubtedly preferable. Nevertheless it has been demon- 

 strated that any applications made to citrus trees during the com- 

 paratively dormant season in October and November, with a second 



