Gasohol

The reagent appears to be methylrosaniline chloride.

See U.S. Pat. 5,229,295 issued to Basil B. Travis of Lodi, CA.

A colorimetric test for alcohols (any alcohol) comprises
0.1% gentian violet dye in mineral oil suspension which
when shaken with fuel causes the fuel to become purple
when there is at least 1% alcohol present. The purple color
is proportional to the alcohol concentration in the range 1%
to 5% where the percentage of alcohol may be estimated
by the intensity of the purple color.
snip
As it is perhaps well known, gentian violet dye is chemically
methylrosaniline chloride and has been used as both a
bacteriological and histological stain ...


Wow we're getting somewhere.

I wonder why he quit packaging it and selling the stuff.

Paul
N1431A
KPLU