36 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
aid strength and has long been used as an insecticide wash. It is made 
from various fish oils and fish-oil residue with caustic soda. Better 
success attends (he use of jelly soaps made directly from fish oil and 
concentrated lye. with water, using about three gallons of water, three 
pints of fish-oil, and one can of lye. Various preparations of this nature 
can easily be made. Coarse grease does not make so good asoap as oils. 
The whale-oil soap sold in the stores is used in solutions of one pound 
in two to five gallons of water, experiment being necessary to deter- 
mine what strength will be efficient. The jelly-soap made as mentioned 
above has been successfully used on Aphides, when fresh, in strength of 
1 pound to 8 gallons of water. For most work, however, it would need 
to be stronger. 
Petroleum Products: Kerosene, Naphtha, etc. — Among the washes of an 
insecticide nature which kill by contact there is probably nothing equal 
to the preparations from petroleum. Of these it is only necessary to 
notice those made from kerosene, as experience has fully demonstrated 
the value of this product for insecticide work. In most instances either 
the low or high grade can be used with equally good effect. Kerosene, 
naphtha and some of the lighter products of petroleum have beeu used 
pure. 
Naphtha and the lighter products of petroleum can be used in this man- 
ner with safety to most plants, but the destructive effect on the insects 
is by no means satisfactory. The use of kerosene pure is, however, at- 
tended with danger and should never be undertaken except in a small 
way and with the utmost care. Finely atomized, I have employed it with 
some success, especially on oranges and certain conifers in years gone 
by, before the emulsions were discovered. 
Kerosene Emulsions. — The ease and practicability of emulsifying and 
diluting kerosene to any desired strength have been so fully demon- 
strated in the course of the work of the division of entomology under 
my direction that there is no longer need of attempting its use pure. 
The methods of emulsificatiou have been so fully set forth elsewhere 
that it is unnecessary to undertake their discussion here more than 
in the nature of general instructions. 
An emulsion, if properly made, always contains a greater per cent, 
of kerosene than of the other ingredients. This per cent, may vary 
from 60 per cent, to 90 per cent., but experiment has shown that 66 per 
cent kerosene will give the most satisfactory results. 
The formula for the preparation of kerosene emulsion ordinarily 
recommended by me is the one originated by my former agent, Mr. H. 
G. Hubbard, in his work against orange insects. It is as follows: 
Kerosene - 2 gallons = 67 per cent. 
Common soap, or whale-oil soap i pound ( _ 33 ,, er cent 
Water 1 gallon $ ] 
Dissolve the soap in the water by heating and add the solution, 
boiling hot, to the keroseue and churn the mixture by means of a 
