59 
of the oil, but also of the water necessary to hold the oil in emul- 
sion, and the kerosene slowly separates as the emulsion dries up 
and hardens. 
“The churning can be done very satisfactorily through an ordin- 
ary force-pump, such as the well-known aquepult, it being repeat- 
edly forced from one vessel to another. If sour milk is used there 
will be no further fermentation, and when kept protected from the 
open air in a tight vessel the butter endures for any length of time. 
The emulsion may be made of any desired strength, as the quan- 
tity of milk required to hold the oil does not exceed ten per cent. 
Emulsions containing over eighty per cent. of oil are, however, not 
readily held in suspension in water, on account of their light specific 
eravity,—yet those containing less than thirty per cent. of oil lose 
value as insecticides, as the oil loses some of its power in becoming 
emulsified. In other words, the killing-power of a diluted emulsion 
depends, not so much on the amount used, as on the percentage of 
oil contained in it. Churn until the whole solidifies and forms an 
ivory-white, glistening butter, as thick as ordinary butter at a temper- 
ature of 75° F'.; if the temperature of the air falls below 70°, warm the 
milk to blood-heat before adding the oil. The diluted wash resem- 
bles fresh milk, and if allowed to stand, in two or three hours the 
emulsion rises as a cream to the surface. The butter should there- 
fore be diluted only as needed for immediate use, and the mixture 
should be stirred from time to time.” 
My experiments with kerosene were made first upon hills of corn 
transplanied to the laboratory, and the results were always verified 
afterwards by application in the field upon a larger scale. The 
emulsions used were of various strengths and composition, and were 
variously diluted with water, soapsuds, and a solution of potash. 
The following table of solutions and emulsions will be convenient 
for reference in describing the experiments: 
Solutions with which Dilutions were made. 
" Soapsuds BI Fete. o ts ooh ree eras Soe eae Bes aeeceseioes bases i Ib. soap to ae gal. water 
So TRAGIC 6 2" Se GE eee eae es oe aa ne ae ge em ge WSO qayayteisyay Co Gl) CO sie 
Exnulsions as diluted. 
Per cent. of 
7 Kerosene. 
Ap ADArisekerosene. Llopart milk, 45 parts water. ....-<0+--csesss.ccemeceecceccseoee 4 
iBalepar rs ay oe Si os SOO SS) ES CR ad See Ree ae a ees aes 5 
Coy 1. * Og ers DELLS ee ES OLUGION.L moc. ee eee eee eee een tae 5 
IDs. kof ae eae biased deta ‘oie ae re Dirk SEES. 2 eee ene Sr ea aye 2% 
1D fn ae . ihe oO Seas CIV LOLS cee oor ee eso ard 236 
pe eoliniy * tas Ty 2S een OSusminiy S OLUMO lioicnce ca. ee ceat eee cose eer eene oe 236 
Gert e re Oe tae TON att Hig Di oe atte een Bot a nek side ale 3 
15 lo) Lea : I SOlItLOn ll) lepanrts Solution ces aeaeeeeee ence sees cere e 5 
1 Pea hea as 1 Ry cs 1a Be <e EEO CRE eee Oe 62 
On the 22d of July, I transplanted several hills of corn to the 
laboratory, placing them in boxes about a foot and a half wide by 
two feet in length. The corn was from two to three feet in height 
at this time. Each hill was infested with several hundred chinch- 
bugs, which were of various sizes below the pupa stage. They were 
largely hidden behind the sheaths of corn, but were akso exposed 
above the leaves and upon the outer surface of the sheaths. All 
