I remember a discussion here a few weeks ago about a 3 and some symbols on another medicine bottle. This has it embossed as well on the reverse side. I think it is dosage and or # of doses.
Hey there David. What you've got there is a pretty nice example of a pharmacy bottle probably from the 1930s to the 50s. The 3iii is the measurement. I could probably use some of that stuff right now on my arms and legs [] The below response is talking about the same subject but with a guy who's bottle has 3iv on it instead of 3iii so I hope it doesn't confuse you!
"It's a common enough bottle that it merits a response to help others.
The 3iv designation is a pharmacist's terminology for 4 ounces. If you really want to dig into this issue, then roll up your sleeves and get ready to digest the somewhat confusing notion that this is a matter of the relation between weight and volume of an ounce. The way I understand it, such a bottle would contain 4 ounces by weight and not by volume." From http://forum.antiquebottles-glass.com/discussion/121/bottles-marked-with-3iv-and-duraglas/p1
Very interesting, I remember the volume / weight terminology from chemistry class in college. According to the website, this bottle has 3ii embossed. This would mean it's 2oz size liquid. Thanks for posting that link.