Here is what I've been working on lately....

[MoonDawg]

         I remember as a kid living on the farm, gasoline tax only applied to vehicles
using public roadways. A purple dye was added to non taxable gasoline which was
only to be used by farm equipment like tractors and combines.
         Some farmers were randomly pulled over and the cop would siphon a small
amount of gas from his truck to make sure he was not burning purple gas. Could
this have any relation to the site glass on early pumps?