EMULSIONS OF KEROSENE PREPARATION OF. 157 



arated soon and rose to the surface of the water, but the larger por- 

 tion of the oil remained suspended in the water for a considerable length 

 of time. Whatever were the shortcomings of this discovery at tlie time, 

 we called attention to it in a communication to the Scientific American * 

 and it is difficult to understand why its importance was not fully ap- 

 preciated by all interested in economic entomology. As it was it proved 

 to be the stepping-stone to the successful solution of the problem of 

 mixing kerosene with water without changing the nature of the former. 

 This mode of obtaining a perfect and stable emulsion was discovered by 

 Mr. Hubbard while experimenting with kerosene for scale insects affect- 

 ing the orange tree. We quote his description of it.t 



" The i^rocess of forming a perfectly stable emulsion of kerosene and milk is compar- 

 able to that of ordinary butter making, and is as follows; The oil and milk in any 

 desired proportions are poured together and very violently dashed or churned for a 

 period of time, varying with the temperature, from fifteen to forty-five minutes. The 

 churning, however, requires to be much more violent than can be effected with an 

 ordinary butter-churn. 



' ' The Aquapult force pump * * * may be satisfactorily used for this purx)ose where 

 moderate quantities only are required. The pump should be inserted in a pail or tub 

 containing the liquids, which are then forced into union by continuous pumping back 

 into the same receptacle through the flexible hose and spray-nozzle. After passing once 

 or twice through this pump the liquids unite and form a creamy emulsion, in which 

 finely divided particles of oil can plainly be detected. This is as far as the process 

 can be carried by stirring or by dashing in an ordinary churn ; the product at this 

 point will not bear diluting with water and separates or rises at once to the surface. 

 On continued churning through the pump the liquid finally curdles and suddenly 

 thickens to form a white and glistening butter, perfectly homogeneous in texture, and 

 stable. 



''The whole amount of both ingredients solidify together, and there is no whey or 

 other residue; if, however, the quantity of the mixture is greater than can be kept 

 in constant agitation, a portion of the oil is apt to separate at the moment of emulsi- 

 fication and will require the addition of a few ounces of milk and further churning 

 for its reduction. 



" This kerosene butter mixes readily in water, care being taken to thin it first with 

 a small quantity of the liquid. The time required to " bring the butter" varies with 

 the temperature. At 60° F. it is half to three-quarters of an hour; at TS*^, fifteen 

 minutes, and the process may be still further facilitated by heating the milk up to, 

 but not past, the boiling i^oint. Either fresh or sour milk maybe used, and the latter 

 is even preferable. 



'•' The presence of kerosene does not prevent or hinder the fermentation of the milk ; 

 on standing a day or two the milk curdles, and although there is no separation of the 

 oil the emulsion thickens and hardens and requires to be stirred, but not churned, 

 until it regains its former smoothness. 



*' If sour milk is used no further fermentation takes place, and if nor exposed to the 

 air the kerosene butter can be kept unchanged for any length of time. Exposure to 

 the air not only permits the evaporation of the oil but also of the water necessary to 

 hold the oil in emulsion; the kerosene slowly separates as the emulsion dries up and 

 hardens. 



" Kerosene emulsions may be made of almost any strength; the quantity of milk re- 

 quired to hold the oil does not exceed one-tenth. But emulsions containing over 80 

 ])er cent, of the oils have too light a specific gravity and are not too readily held in 

 suspension in water. On the other hand, the process of emulsification, kerosene loses 



* Scientific American, October 16, 1880. 



tAunual Keport Department of Agriculture, 1881-'82, pp. 112, 113. 



