I usually whip them into the weeds when I find them. However, I've never seen one embossed on the bottom...cool. I always check before I whip anything.
The small ones like that are dose vials. The contained enough med for a single injection. Most had a rubber end and the needle when through it. I have dug them in amber and yes cobalt. The larger ones in that style mostly held toothache powder etc. I have several of the labeled versions in the larger size. There was a old DR'S house site dump I dug it was from the 20's there were tons of those and the glass syringes in there. The ones marked pyrex are not as old as most. Pyrex made a ton of med related containers and vials in the 30's-40's era.