156 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
Agriculture: -'The requisite amount of kerosene and water is placed in 
a barrel or pail, and with the syringe a syringeful several times squirted 
into the barrel, when the mixture must be quickly applied before the 
oil aud water separate." When converted into soap by means of lye and 
boiling, kerosene, like any other oil, can easily be diluted with water to 
any extent, but loses in this form much of its deadly quality ; hence its 
application in soap form has but little effect on the Cotton Worm, though 
it is more useful for many other insects more readily affected by sapo- 
naceous compounds. 
When mixed with a sufficiently large quantity of wood ashes, kero- 
sene can be applied to the leaves without damaging them, but the mix- 
ture cannot be sprinkled in particles small enough to have much effect 
on the worms. A patent was obtained by Mr. George W. Powell, of 
Halifax County, Virginia, in April, 1876, for the simple mixture of one- 
half pint of kerosene to one quart of fine, dry, well-sifted wood ashes. 
The patentee claims that by sprinkling or scattering this preparation 
lightly over the plants it will drive off or destroy insects of every kind 
without injury to the leaves. 
An attempt has been made to apply the oil in form of vapor by means 
of steam. There is no question but that the worms are killed by this ap- 
plication, and, perhaps, without injury to the plant; but the machine 
necessary for the production of the vapor, which will be described fur- 
ther on, is so ponderous and awkward as to be of no practical value. 
The above-mentioned methods of applying kerosene are of little or no 
value in our warfare against the Cotton- Worm but an important step to- 
ward a practical solution of this difficult question was made in the summer 
of 1880. Professor Barnard, while in the field at Selma, Ala., suggested 
the use of milk as a medium to facilitate the mixing of kerosene and 
water. First it was found that the oil mixes much more readily with 
the milk than with water. If a small quantity of the oil is stirred up 
in a much larger quantity of milk, the oil particles will remain much 
longer suspended in the milk than in water, thus permitting a practical 
application of the mixture. It was further found that even a large pro- 
portion of the kerosene could be mixed with milk by violently shaking 
up the closed vessel containing the mixture. Thus one part of kerosene 
to two parts of milk would unite after several minutes' shaking to form a 
kind of emulsion, in which the two ingredients did not separate until 
after many hours, and which then could always be restored, by shaking, 
to its apparently homogeneous condition. Though, in the light of subse- 
quent discoveries, this emulsion proved to be a very imperfect one, and, in 
fact, no emulsion at all, but only a more or less finely divided mixture of 
the oil and milk, still it was found most useful for experimentation on a 
small scale aud vastly superior to any of the old methods of applying 
kerosene. There was no difficulty experienced in experiments on a small 
scale in diluting this emulsion of one part of kerosene with three parts 
of milk with any desired quantity of water. A portion of the oil sep- 
