Circular 21 - Insecticides and Subsidiary Materials 35 
Fuel oils ordinarily have a somewhat 
higher boiling point than kerosene. The 
lighter fuel oils are somewhat kerosene-like 
in character. In color they may De clear or 
yellowish to somewhat brownish, depending on 
the type of crude petroleum from which they 
are derived. The chief use of fuel oil is 
for oil burners, to provide heat for houses, 
commercial establisliments , or industrial 
processes. 
Caution ; Fuel oil is inflammable. 
Spontaneous combustion of oil-soaked rags left 
in poorly ventilated places may occur. 
Fuel oil is obtainable at most oil refin- 
eries and from local distributors. Available 
on contract: see Class lUt General Schedule 
of Supplies, Procurement Division, Treasury 
Department. 
GARDHTOL ^. A. 
Gardinol '^V. A. is used as a substitute 
for soap and as an emulsifying- agent in the 
preparation of mosquito larvicides such as 
emulsions of pyrethruia extract in kerosene oil. 
This or a similar exmulsifier is an essential 
component where larvicides are to be used on 
water having: a salt content higher than 5 per- 
cent. Larvicides containing soap cannot be 
used in such situations because the salt water 
would precipitate the soap. The spray emulsion 
is diluted for use at the rate of 1 part to 10 
parts of water and then sprayed over the surface 
of mosquito breeding areas such as pools, 
ditches, streams, and the like. It is used 
also as a wetting and spreading agent in the . 
preparation of various other horticultural 
sprays. 
