EMULSIONS OF PETROLEUM; THEIR VALUE OF INSECTICIDES. 447 
SCIENTIFIC MISCELLANY. 
EMULSIONS OF PETROLEUM AND THEIR VALUE AS 
INSECTICIDES. 
» C. V. RILEY, PH.D., WASHINGTON, D. C. 
\_Abstract.\ 
The value of petroleum for the destruction of insects has long been recog- 
nised, and I have for years been endeavoring to solve the question of its safe and 
ready use for this purpose without injury to plants. The paper contains the 
results of extended experiments carried on under my direction, by several of my 
assistants and particularly by Prof. W. S. Barnard, Mr. Joseph Voyle, of Gaines- 
ville, Fla., Mr. Clifford Richardson, assistant chemist of the Department of Agri- 
culture, and Mr. H, G. Hubbard, who has for over a year been devoting his 
time to practical tests in orange groves at Crescent City, Fla. 
Passing over the ordinary methods of oil emulsions by phosphates, lactophos- 
phates and hypophosphites ol lime and various mucilaginous substances, exper- 
ience shows that, for the ordinary practical purposes of the farmer and fruit- 
grower, soap and milk are among the most available substances for the production 
of petroleum emulsions. 
Ordinary bar soap scraped and rubbed into paste at the rate of 20 parts soap, 
10 parts water, 30 parts kerosene and i part of fir balsam, will make, when diluted 
with water, an emulsion stable enough for all practical purposes, as the slight 
cream which in time rises to the surface, or the flakiness that often follows, is easily 
dissipated by a little shaking. Soap emulsions are, however, less satisfactory 
and efficient than those made with milk. Emulsions with milk may be made of 
varying strength, but one of the most satisfactory proportions is 2 parts of refined 
kerosene to i part of sour milk. This must be thoroughly churned (not merely 
shaken) until a butter is formed, which is thoroughly stable and will keep indefin- 
itely in closed vessels and may be diluted ad libitum with water when needed for 
use. The time required to bring the butter varies with the temperature, and both 
soap and milk emulsions are facilitated by heating the ingredients. Ordinary 
condensed milk may also be used by thoroughly stirring and beating it in an equal 
or varying quantity of kerosene. 
The diluted emulsion when prepared for use should be finely sprayed upon 
the insects to be killed, its strength varying for different insects or plants and its 
effect being enhanced when brought forcibly in contact with the insects. 
Of mucilaginous substances, that obtained from the root of Zaniiaititegrifolia, 
a plant quite common in parts of Florida, and from the stems of which the Florida 
arrowroot is obtained, has proved useful as an emulsifier. 
