This is an antique late 1800s cobalt blue glass medicinal poison bottle with original glass stopper.

In the late 1800s, the American Medical Association imposed a law that all medical bottles that may have dangerous contents have some sort of ribbed markings, corrugated markings, ornate markings, skull and crossbones, and or read “POISON” or “NOT FOR CONSUMPTION.”

Interestingly, antique medical poison bottles tend to be more attractive and more collectible than their counterparts from the same time period. For example, a plain medical bottle from the late 1800s you can find on ebay for a few dollars while poison bottles are more expensive.