160 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
idea being that the excess of the oil on the surface of the lea ves would 
be taken up by the ashes, and thus prevented from entering into the 
system of the plant, while at the same time the ashes would not inter- 
fere with the effect of the oil upon the worms. 
The following account of Dr. deal's experiments with improved kero- 
sene emulsions is from his report, published in Bulletin 1 of the En- 
tomological Division : 
As directed, I liave confined my experiments to emnlsions of kerosene, and noted 
the effects of applications of such solutions upon the cotton-plauts and Cotton Worms. 
My efforts were made to determine: 1. Substances best adapted to emulsify kero- 
sene; 2. Maximum dilution of kerosene destructive to the larvae; 3. Minimum dilu- 
tion of kerosene destructive to the cotton-plants. 
It was soon apparent that kerosene could not be used to advantage simply with 
water, from its tendency to collect at the top; nor if the water were made slightly 
;ilkaline or acid would much benefit be observed. 
A strong solution of vari us soaps made a good emulsion, presenting some points erf 
advantage. 
Soda soap, potash soap, whale-oil soap, and other varieties were tried, but a cheap 
grade of yellow bar-soap, especially one in which rosin was largely used, proved best, 
and suggested the manufacture of a soap containing a still larger quantity of rosin, 
which could be cheaply sold for this purpose. 
After many trials I found that 4 pounds of this soap to 1 gallon of hot water would 
emulsify 1 gallon kerosene, forming a gelatinous compound tbat was quite stable. 
Less than this percentage of soap acted badly with kerosene, and a greater amount 
did not appear to emulsify a large amount of kerosene. 
This mixture, containing 50 per cent, kerosene and costing "26 cents per gallon, I 
adopted as a standard. 
I prepared the following dilutions : 
A. One gallon standard solution to 24 gallons water, 2 per cent, kerosene, cost 1.04 
cents per gallon. 
B. One gallon standard solution to 39 gallons water, 1.25 per cent, kerosene, cost 
0.65 cents per gallon. 
C. One gallon staudard solution to 49 gallons water, 1 per cent, kerosene, cost 0.52 
cents per gallou. 
D. One gallon standard solution to 79 gallons water, 0.625 per cent, kerosene, cost 
0.325 cents per gallou. 
E. One gallon standard solution to 99 gallons water, 0.5 percent kerosene, cost 0.26 
cents per gallon. 
Emulsions A. B, and C presented a milky color, and were quite permanent; D and 
E showed some tendency to disintegrate after four days' standing. 
I tried solutions of many native plants, and found the zamia finely adapted for an 
emulsion, especially when used immediately. 
Six pounds of zamia "roots" were washed aud grated. The pulp boiled an hour 
la 3 gallons of water ; then strained, and while lu)^ stirred in 4 ounces sal-soda. This 
emulsified 1 gallon kerosene, forming a beautiful pinkish jelly, containing 25 per cent, 
kerosene, costing 6 cents per gallon. One gallon of this solution was added to 24 gal- 
lons of water. This emulsion contained 1 per cent, kerosene, and cost 0.24 cents per 
gallon. 
Dextrine, starch, flour, mucilage of bene (sesamum) leaf, mucilage of root of rteris 
nt/iiilinu, and other substances were tried, but proved to be of little value. 
Milk emulsion*. — By gradually adding, with agitation, one gallon kerosene to one 
gallon fresh milk, an elegant emulsion was formed that bore dilution well, bnt as 
fresh milk is often not attainable the condensed milk was used, and the following 
seemed most easily made: 
One part condensed milk dilute with five parts water ; to this add gradually eight. 
