Circular 21 - Insecticides and Subsidiary Materials 31 
The cost of ethylene oxide in steel 
cylinders ranges from 50 to 55 cents per pound. 
The mixture of 1 part of ethylene oxide and 
9 parts of carbon dioxide by weight is sold in 
30 to 60 pound cylinders under high pressure 
at prices ranging from 14.5 to 16 cents per 
pound, f.o.b, factory. 
For manufacturers and distributors see 
numbers 21 and 36 of list at end of this 
circular. 
FLY SPRAYS 
Fly sprays are used to kill house flies 
or flies affectin^i!; livestock, mosquitoes, 
fleas, and certain other insects. A great 
number of commercial fly sprays or household 
insecticides of the liquid spray type are now 
available. For the most part these consist 
of certain combinations of highly refined 
petroleum oils with pyrethrum extracts, derris 
extracts, or organic thiocyanates added as 
the active insecticidal ingredient. They may 
vary considerably as to the nature or quanti- 
ties of ingredients used. As a result of the 
need for some standard by which sprays of 
this type could be evaluated, the National 
Association of Insecticide and Disinfectant 
Manufacturers, Inc., The National ^ureau of 
Standards, and other interested organizations 
and individuals have cooperated in establish- 
ing specifications for the liquid spray type 
of household insecticides. The establishment 
of the standard was announced June 10, 1933. 
The specifications agreed upon and discussion 
are contained in the publication, "Commercial 
Standards CS 72-3S," by the National Bureau 
of Standards, Department of Conunerce, 
Washington, D. C. 
