THE COLORADO EXPERIMENT STATION 
3 6 
tains it until all is a frothy, creamy mass. If such a mixture is not 
obtained in a very few minutes, put the whole over the fire again 
until it boils and then repeat the pumping, and the emulsion will 
almost surely form. When put back for reheating, watch every 
moment to see that it does not boil over and take fire . This work 
should be done out of doors. After the emulsion is made, add the 
remaining 27 gallons of water and all is ready for use. 
Small quantities may be emulsified with a rotary egg-beater. 
Whale-oil soap, or any cheap soap, may be used. 
Clean dishes and clean water should be used. Every particle 
of dirt in the emulsion serves as a center of attraction about which 
the oil droplets will collect and then rise to the top to form a film 
of oil on the surface. 
The strength above given is suitable for most insects. Most 
plant lice may be killed with an emulsion of half the above 
strength. 
15. KEROSENE-MIEK EMULSION. 
Kerosene will emulsify with milk, also, and when small quan¬ 
tities are wanted it is often less trouble to use the milk than to 
prepare the soapy water. These proportions are: 
Milk (sour).-I gallon 
Kerosene.2 gallons 
Dilute with water as in the preceding formula. If sweet milk 
is used, add a little vinegar. Otherwise it may be impossible to 
form a stable emulsion. 
16. KEROSENE AND CRUDE PETROLEUM. 
These oils are used pure, and also diluted with water, for the 
destruction of scale and other insects. Experiments in the Eastern 
States seem to indicate that the safest time to apply .is early in the 
spring, just before the buds swell, and on a bright, windy day when 
the oil will evaporate rapidly. It seems that when applied in 
moderation, in the proportion of 40 parts of the oil to 60 of water, 
these substances will -seldom injure apple, cherry or pear trees, 
but can hardly be applied to tenderer trees, such as peach and 
plum, without further dilution. 
When diluted with water in the form of a spray they may be 
used upon foliage of most plants, without injury, in the proportion 
of one of the oil to five or six of water. Most plant lice are killed 
in mixtures as weak as one of oil to fifteen or twenty of water. 
Pumps are now made for the purpose of mixing the oil and 
water in the form of a spray, and so do away with the need of 
preparing an emulsion. The one who has the insecticides to appl) 
