As Frank points out, they were not made excusively by Chance, but were probably the largest producer. I believe the Chance ones are double-opal-flashed (inner core of clear), but whether ones produced by other companies are the same, I have no idea.
If you do see these, then do snap them up as they are quite collectable - not sure when plastic ones were used, but probably 1960s?
I have some photos of ones made by Chance, and dating to around mid-1950s: Shell was one make (nice shape) and others include BP (two types), Regent, Clevecol. There are other advertising globes that might not be related to petrol, which are of equal interest to me in preparing for the second book.