398 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
Milk as an Emulsifier of Mineral Oil. The standard dormant 
spray, lime sulfur, has failed to give satisfactory control of severe cases of 
scale in different parts of the country, while experimental tests have 
shown that the miscible oils and the home made fish-oil emulsions have 
given excellent results. Accordingly, the demand for oil emulsions has 
increased. Yothers 2 has outlined a method for the home preparation 
of engine oil emulsions by means of potash fish-oil soap. This method, 
however, involves considerable labor and the time necessary to prepare 
it is usually not available when the spray must be applied. Burroughs 
and Grube 3 , improving upon the suggestions of Pickering 4 , have de¬ 
veloped several excellent methods by which different materials may be 
used to emulsify mineral oils. As these are prepared without the aid of 
heat they are referred to as “cold” emulsions. The procedures are short, 
and if care is exercised good emulsions may be obtained 
As a water soluble colloid having a low surface tension and a low 
interfacial tension to mineral oil, milk should be an excellent emulsifier 
for this class of oils. Laboratory observations made of many varied 
combinations indicate that the following formula will give good results. 
Mineral oil. 4 gallons 
Water.1.5 gallon 
Milk.1.5 quarts 
Hydrated lime. 2 ounces 
Preparation. To make the emulsion the oil is introduced into a 
half barrel or other suitable container. The milk is added to the water 
and the hydrated lime or slaked quick-lime stirred in the diluted m ilk 
This is then poured into the oil, the mixture pumped back into itself for a 
minute and finally pumped into another container, using as high a 
pressure as possible, and with the opening in the nozzle reduced until a 
fine spray is obtained. It should then be pumped back again to give 
best results. 
It is important to maintain as high a pressure as the spray pump can 
deliver in order to produce a smooth' emulsion. A pressure of 200 
pounds or more is desirable. A bucket pump may be used but the higher 
pressure pump is advised. 
Plydrated lime is used to neutralize the acid reaction of the milk and 
to dissolve the casein. Sodium or potassium hydroxide or sodium car¬ 
bonate may be substituted for the lime, but the latter is preferable, es- 
2 U. S. D. A. Clip Sheet 193, 1922. 
3 Journ. Econ. Entomology, V. 16, No. 6, 1923. 
4 Journ. of Chem. Society, V. 91, 1907. 
