27 CFR 21.22: Formula No. 18.

To every 100 gallons of ethyl alcohol of not less than 160 proof add:

2.50 gallons of either methyl isobutyl ketone, mixed isomers of nitropropane, or methyl n- butyl ketone;

0.125 gallon of pyronate or a similar compound;

0.50 gallon acetaldol (beta-hydroxybutyraldehyde); and

1.00 gallon of either kerosene, deodorized kerosene, gasoline, unleaded gasoline, rubber hydrocarbon solvent, or heptane.