EMULSIONS OF KEROSENE PREPARATION OF. 
157 
•rated 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 the 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. ilubbard while experimenting with keroseue for scale insects affect- 
ing the orange tree. We quote his description of it. t 
" The process of forming a perfectly stable emulsion of kerosene and milk incompar- 
able to that of ordinary bntter 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 bo effected with an 
ordinary hut ter-churn. 
"The Aquapult force pump * • * may be satisfactorily used for this purpose where 
moderate quantities only are required. The pump should be inserted in ■ pail or tub 
containing the liquids, which are then forced into union by cont inaOQfl pumping back 
into the same receptacle Ihrongh 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 bntter, 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- 
Beation and will require the addition of a few ounces of milk and further churning 
for its reduction. 
'• This kerosene bntter mixes readily in water, care being taken to thin it first with 
n small quantity of the liquid. The time required to u bring the bntter" varies with 
the temperature. At 60° P. it is half to three-quarters of an hour; at 75°, fifteen 
minutes, and the process may be still further facilitated by heating the milk up to, 
but not past, the boiling point. Either fresh or sour milk may bo used, and the latter 
is even preferable. 
" The presence of kerosene does not provent 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 not 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 tho water necessary to 
hold the oil in emulsion ; the kerosene slowly separates as the emulsion dries up and 
hardens. 
u 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 90 
per 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. 
t Annual Report Department of Agriculture, 1881-82, pp. 112, 113. 
