20 
oil, and there is even somewhat greater risk, owing to the natural 
tendency one has to apply the dilute mixture much more freely than 
the pure oil The application should be merely enough to wet the 
bark and the mixture should not, to any extent at least, run down 
the trunk, as it is just as dangerous to the tree as the pure oil. 
In the use of the oil sprays noted above, one who has not had expe- 
rience with them is advised to make some careful preliminary tests 
to fully master the process, preferably waiting two or three weeks to 
determine the results before entering on the general treatment of the 
orchard. It is well, also, with the oil-water mixtures to test the pump 
from time to time, spraying into a glass jar or bottle to determine by 
actual measurement whether the correct percentages of oil and water 
are being maintained. 
Kerosene emulsion (soap formula).—The kerosene-soap emulsion, fol- 
lowing chiefly the Riley-Hubbard formula, has been one of the stand- 
ard means against scale insects for twenty years. The distillate 
emulsion generally employed in California for spraying citrus and 
other trees is substantially the same thing, except that it is made with 
the California distillate or petroleum oil. Crude petroleum of any 
kind, as well as the refined product, may also be used in making this 
emulsion. The use of the soap emulsions against the San Jcse scale 
in the East has not been very general, on account of the greater facil- 
ity with which the pure oil or oil-water mixtures can be applied. 
The difficulty of obtaining uniform results with the latter has led to a 
return to the use of emulsions to some extent, and there can be no 
doubt about their superior merit when it is desired to dilute the pure 
ous. Emulsions may be appled at any strength with absolute con- 
fidence that there will be no variation. Where the emulsion can be 
prepared wholesale by steam power, its employment is attended with 
no difficulties. In California it is prepared by oil companies and sold 
at very slightly more than the cost of the oil and soap ingredients. It 
is made after the following formula: 
Petroletmnjs tates )6 sk eho 98 ge urbe al a Pater! Wee Spl gallons__ 2 
Whale-oil soap (or 1 quart soft soap)_____________+____pound__ 34 
Witter: (SOft) = 2 Sate RE 2 URE ok by Be ee gallon__ 1 
The soap, first finely divided, is dissolved in the water by boiling 
and immediately added boiling hot, away from the fire, to the oil. 
The whole mixture is then agitated violently while hot by being 
pumped back upon itself with a force pump and direct-discharge 
nozzle throwing a strong stream, preferably one-eighth inch in diam- 
eter. After from three to five minutes’ pumping the emulsion should 
be perfect, and the mixture will have increased from one-third to one- 
half in bulk and assume the consistency of cream. Well made, the 
emulsion will keep indefinitely and should be diluted only as wanted 
for use. 
127 
RE PA Sages, 
